Modern methods of storing information can be divided into two groups - storage methods on physical media and storage methods based on cloud technologies.

Existing physical storage media include optical disks, solid state media, and magnetic hard drives. Optical discs allow you to store a limited amount of information, have a low write speed, are sensitive to mechanical damage, the effects of temperatures. The most common storage media are solid-state storage media (flash cards, memory cards, solid-state hard drives). They are characterized by high recording speed, small size and resistance to mechanical damage, the amount of vulnerable information is much larger than that of optical disks, but so far inferior to the volumes stored on hard magnetic disks. Magnetic hard drives are characterized by high speed of information recording, high reliability of data storage and large amounts of memory, however, they are very sensitive to mechanical stress.

Recently, cloud storage technologies are gaining popularity. Information is stored on numerous servers distributed on the network, while users do not see the structure of the servers, they work in the cloud - one large virtual server.

One of the most popular cloud-based data storages is Google Drive (https://drive.google.com), which allows you to store 30 types of files, provides tools for working with documents online. The volume of free space is 15GB, you can additionally purchase from 100GB ($ 1.99 per month) to 30Tb ($ 299.99 per month). In addition to accessing the service through the web interface, there is the possibility of access through clients for Windows, Mac OS and Android, iOS.

Microsoft OneDrive cloud storage (http://onedrive.com) is integrated with Office365, which allows you to create, edit, save Excel, OneNote, PowerPoint and Word files in the cloud directly from the application. The service provides the possibility of free storage of 5GB, paid storage from 50GB for $ 1.99 per month, which is two times more expensive than Google Drive.

Dropbox (http://www.dropbox.com) is a cloud-based data storage that provides 2GB of space for free, but allows you to increase this capacity to 48GB by fulfilling a number of conditions (inviting a friend, viewing Dropbox review, installing Dropbox on a computer, placing files in the Dropbox folder, installing Dropbox on other computers that you have access to, sharing with friends and colleagues, installing the application on mobile devices). Paid storage has a capacity of 1TB and costs € 9.99 per month. The advantage of Dropbox is ease of use and high speed. In order to place files in the cloud, just put the files in the Dropbox folder on the computer, open access to it and synchronize with the desired device. When editing files previously placed in the cloud, only part of the copy is copied to the server. Dropbox makes it possible to recover data after it has been deleted from the server, as well as view the history of file changes in 30 days. To ensure privacy, Dropbox offers the BoxCryptor tool, which encrypts files before transferring to the cloud.

The most budget cloud storage is Mega (https://mega.co.nz). The starting free volume is 50GB, and 4TB per month costs $ 8.33. A feature of this repository is privacy concerns. Data is encrypted in a browser, transmitted to the cloud, decryption keys are not published in the public domain, but transmitted between users who trust each other.

Yandex.Disk (http://disk.yandex.ru/) is a cloud storage that provides 10GB free, giving you the opportunity to expand the free volume up to 60GB by participating in promotions. For $ 0.5 per month, you can purchase an additional 10 GB, the cost of 1 TB is approximately $ 3.5. Yandex.Disk is integrated into the Microsoft Office suite, and it also makes it possible to automatically upload photos and video files from digital cameras and external storage media.

[email protected] (https://cloud.mail.ru/) is a cloud storage from Mail.ru that provides free 25GB storage, access via mobile applications for Android and iOS, and a client for Linux. You can automatically upload photos to your cloud from your phone through mobile applications.

Amazon Web Services (https://aws.amazon.com ) - a cloud services platform that supports various storage options (object storage, block storage, file system storage, archive storage, integrated storage), various network solutions (virtual private cloud, direct connection, load balancing), data processing and database generation tools , corporate applications and mobile services. Using the free platform is possible during the first 12 months, and then a fee will be charged for those services that are used.

You can supplement the list of listed cloud storages with the following cloud systems Bitcasa (http://bitcasa.com), Yunpan360 (http://yunpan.360.cn/), 4shared (http://www.4shared.com), SugarSync (https : //www.sugarsync.com), Box.net (http://box.net), iDrive (http://www.idrive.com), OpenDrive (http://www.opendrive.com), Syncplicity (http://www.syncplicity.com), MediaFire (http://www.mediafire.com/), Cubby (https://www.cubby.com/), ADrive (http: //www.adrive. com /).

Under information storage (from keep -keep safe / intact) you should understand the content of the information in the external memory of the computer.

The storage of information involves such concepts as a storage medium (memory), internal memory, external memory, information storage. A storage medium is a physical medium that directly stores information. The main carrier of information for humans is their own biological memory (human brain). It can be called internal memory, because its carrier - the brain - is inside a person. All other types of storage media can be called external (in relation to the person). The types of these media changed over time from stone to paper. The development of information technology has led to the creation of magnetic, optical and other modern types of storage media.

Information storage is a certain way organized data collection on external media intended for long-term storage and permanent use. Examples of repositories are document archives, libraries, directories, and file cabinets. The basic information unit of the repository is a specific physical document - a questionnaire, book, case, dossier, report, etc. Under the organization of the repository is understood the presence of a certain structure, i.e. orderliness, classification of stored documents. Such an organization is necessary for the convenience of maintaining the repository: replenishing it with new documents, deleting unnecessary documents, searching for information, etc.

The knowledge stored in a person’s memory can be considered as an internal repository of information, but it is difficult for us to understand the organization of this repository. The main property of human memory is the high speed of reproduction of the information stored in it. But compared to external storage, human memory is less reliable. Therefore, for more reliable storage, a person uses external media, organizes information storages.

The main properties of the information storage are the amount of information stored, the reliability of storage, access time (i.e., the time to search for the necessary information), the availability of information protection.

Information stored on computer memory devices is commonly called data. Organized data storages on external computer memory devices are commonly called databases.

In modern computers, the main storage media for external memory are magnetic and optical disks. Consider how the storage of information on magnetic disks is organized. This approach is justified by the fact that optical disks for this purpose began to be used much later, and therefore, in order to ensure compatibility with magnetic devices, they largely imitate the structure of the latter.

Posting information oncarriers. A conventional magnetic disk has two surfaces suitable for hosting information, which is commonly referred to in the technical literature as the side of a disk. Considering that several hard disk drives can be mounted on the same axis in hard disk drives, the total number of sides can be even larger.

Each surface is serviced by its own magnetic head. All heads are assembled into a single mechanical unit and can move along the radius of the disks, and this movement is discrete, i.e. the heads occupy only strictly defined positions relative to the disk. Finally, each track is divided into separate sectors(sector) (Fig. 1.4). A sector is an indivisible piece of information and can only be read in its entirety. The last coordinate of the information on the disk is the number of the required byte in the sector.

So, the position of the information byte on the magnetic disk is determined by four “coordinates”: side number, disk track number, sector number and byte number in it. Such a data storage system is complex and requires some effort to retrieve it. Therefore, special programs have been created that allow the user to extract the necessary data without requiring him to know all these coordinates.

Data storage units.When storing data, two problems are solved: how to save data in the most compact form and how to provide convenient and quick access to them (if access is not provided, then this is not storage). To ensure access, it is necessary that the data have an ordered structure, and at the same time there is a need to additionally write down address data. Without them, you cannot access the necessary data elements included in the structure.

Since the address data is also sized and also subject to storage, storing data in the form of small units, such as bytes, is inconvenient. They are inconvenient to store in larger units (kilobytes, megabytes, etc.), since incomplete filling of one storage unit leads to storage inefficiency.

As a unit of data storage, an object of variable length, called a file, is adopted. A file is a sequence of an arbitrary number of bytes with a unique proper name. Typically, data of the same type is stored in a separate file. In this case, the data type determines the file type.

The file definition focuses on the name. It actually carries the address data, without which the data stored in the file will not become information due to the lack of a method of access to it. In addition to the functions associated with addressing, the file name can also store information about the type of data contained in it. For automatic tools for working with data, this is important, because by the name of the file they can automatically determine an adequate method for extracting information from the file. Obviously, the file name must be unique, as this provides unambiguous access to the data.

The concept of file structure.File storage is organized in a hierarchical structure, which in this case is called the file structure. The top of the structure is the name of the medium on which the files are saved. Then the files are grouped into directories (folders), inside of which subdirectories (folders) can be created. The file access path starts with the device name and includes all the names of directories (folders) through which it passes. The delimiter is the “\\” character (backslash).

The uniqueness of the file name is ensured by the fact that the full file name is considered to be the file’s own name along with the path to access it. It is clear that in this case on one medium there cannot be two files with identical full names.

An example of writing the full file name:

<имя носителя>\<имя каталога1 >\...\<имя каталогаM>\ <собственное имя файла>

It should be borne in mind that sectors with information from a single file are not necessarily located in order in one place on the disk. When recording, the system actively uses the free space that is created when deleting unnecessary files. As a result, certain parts of the file may well fall into different areas of the disk, which will noticeably slow down access to information. To eliminate this phenomenon, operating systems usually include special file defragmentation utilities.

This approach to organizing data storage has historically been due to the fact that magnetic disk drives were used as the material data carrier. In this case, the surface of the disk onto which data was recorded was formatted: it was divided into tracks and sectors. Formatting programs created a 512-byte sector. Thus, as a rule, several sectors are required to write data belonging to one file. The figure clearly shows that the sectors on the outer tracks of the disk are larger than those closest to the center. This suggests that track data should be recorded more reliably. Therefore, the zero track, which serves to store the most important system information, is always located on the outer ring of the disk surface.

How to ensure the safety of information? Do not rush to answer this seemingly simple question. To get started, carefully study the advantages and disadvantages of available storage. Manufacturers will help you with the pros, and we will raise the pitfalls from the abyss of information together in this article.

How to ensure the safety of information? What materials should I use? What to consider when choosing storage media? Do not rush to answer these seemingly simple questions. First, you should carefully study the advantages and disadvantages of the available storage facilities. Manufacturers will help you with the pros, and we will raise the pitfalls from the abyss of information with you in this article.

Sometimes in order to save vital information, a random napkin or an old business card is enough. But for storing a financial report or video from a recent corporate party, such means of storage are hardly suitable. In addition, there are huge amounts of information of legal, commercial, historical or scientific value. It must be stored for years or even centuries, and therefore the choice of storage medium is of paramount importance. What to choose in the dynamic world of technological innovations and old proven media? We bring to your attention an overview of the main means of storing information from their most unsightly side.

Paper

Paper is the oldest medium for storing information. As you know, a spontaneous change in the properties of paper as a result of aging is associated with a change in the chemical structure and, in particular, its main component - cellulose. The development of technology has positively affected the quality of materials used in the production. New technological procedures have significantly improved the physical, chemical and electrostatic properties of paper. Scientific advances have also led to the emergence of more advanced ways of printing information: soot and feather ink, pencils, fountain pens, printing ink, ribbons for typewriters, and printer inks.

The method of applying information, as well as the quality of the material itself, ultimately determines the long-term storage of data on paper. Our ancestors wrote letters with a stylus or ink based on carbon, which does not change its properties for centuries and is a chemically resistant substance. The text is usually applied using physical damage to the surface - the method of punching. The same technology worked on typewriters and matrix printers, in which inorganic dyes were sprayed using a contact method: first the paper was pressed through, and then the dye penetrated the material to a predetermined depth.

This old method of applying information through mechanical punching is not comparable to what is used today in conventional inkjet and laser printers. An inkjet printer sprays liquid ink from a specific distance without physically changing the surface. Manufacturers do not disclose the depth of ink penetration, however, as well as what they are made of. With laser printers, the situation is even worse. According to the technology, the toner powder is applied to the paper, then the sheet passes through the rollers heated to a high temperature, and the powder granules are sintered. In this case, the toner in the paper is often not absorbed at all. There are cases when, after a few years, the paint simply fell off the sheet in whole pieces, like fragments of an old mosaic.

camera roll

With film, things are much better than with paper.

Firstly, the production technologies of at least black and white films are time-tested. They practically do not change, therefore it is safe to say that the materials will be preserved for a long time, even if you buy the most ordinary film from the nearest photo store. At the same time, the chances of a long life for professional films are certainly higher, since they differ from amateur ones in special additives that slow down the aging process. However, the requirements for storage conditions of professional films are somewhat more stringent.

Secondly, unlike paper, film has an expiration date during which manufacturers guarantee the preservation of its properties. After this time, a chemical process begins that causes aging of the film, which can be restrained while observing the temperature, humidity and light storage conditions.

A significant drawback in working with photographic film is that the cost of film and equipment (a camera or a camera, reagents for developing and fixing a picture, projectors for viewing finished materials) is relatively high.

Magnetic tape

Surely you remember your old cassette recorder, which was later replaced by video players and VCRs. The information carrier in them was removable cassettes. With the development of information technology, magnetic tape was also used to store information in digital form.

Special devices (streamers) digitally record information on tape to tape, which is stored in approximately the same way as on a computer: in the form of files. Previously, tape drives were widely used for storing backup copies of data. In everyday life, such devices did not take root. First of all, this is due to the difficulty of accessing the information recorded on the tape. First, you need to rewind it to the place where the necessary information is recorded, and then wait until the data is read into the computer's memory. Not everyone has the patience for such technological troubles. At one time, expansion cards for a computer were produced, with which it was possible to store data on audio tapes, and later on video tapes, using an audio or video recorder in conjunction with the card that is inserted into the computer.

The long-term storage of information on magnetic tape is largely dependent on the quality of the tape itself. For example, there are low-quality tapes, the magnetic layer of which simply crumbles over time, and if you see noise on the video, reading digital data from such a tape will be problematic. A special tape for the streamer is designed for longer storage of information and more active use. This is due to the fact that when writing to tape, special encoding of information is used, which allows you to reliably restore it when reading even if some bits of information are decoded incorrectly (the user will not notice anything). In addition, when recording, several copies of data can be created at the same time (several tracks can be written to the width of the film at the same time), which also positively affects the storage duration.

The problem that potentially awaits every lover of magnetic film is the rapid obsolescence of equipment. It’s not a fact that in a few years, if the current device breaks down, you will be able to find a replacement for it, even just to read the data and transfer it to a new medium. Another unpleasant moment when working with magnetic tape: cassettes need to be rewound regularly. Otherwise, the adjacent layers of the film magnetize each other, which means that the magnetic tape will not be able to reliably store information for a long time. In industrial equipment, robotic systems are used that automatically change cassettes as they fill up and periodically rewind tapes.

Films should be stored with extreme caution, since the magnetic fields that surround us and are completely invisible can damage the information on the tape. So, it is not allowed to use ferromagnetic metal shelving. When placing the film on steel racks, it is necessary to demagnetize and close the contours of the rack: the connection of the metal parts of the rack with an electric wire and their effective grounding. It will not be superfluous to recall that a magnetic film, like any carrier, also requires compliance with a certain temperature and humidity regime.

Floppy disks

Floppy disks are the last century. In a literal sense. They were popular from the 1970s to the end of the 1990s, when they replaced the more capacious and convenient CDs, DVDs and flash drives. Disk drives for 3.5-inch floppy disks are still available for sale, but they are practically not installed on modern computers. The reason for the disappearance is obvious - a small amount of information stored on a diskette (1.4 megabytes) and low reliability. The same requirements apply to storing floppy disks as to magnetic films.

CD / DVD

Low cost and general availability are the main advantages of CDs and DVDs. But, unfortunately, the information on them is often completely (or partially) lost in two or three years. This is due to the destruction of the coloring layer caused by exposure to sunlight and ionizing radiation.

Sometimes in the production of large batches, stamping is used, similar to the production of vinyl records. Unlike regular CDs and DVDs, such discs can last for years.

Manufacturers claim that, subject to storage conditions, some types of discs (CD-R, DVD-R) can be used from 100 to 200 years. However, in practice these optimistic statements are not confirmed.

Hard Disk Drive (HDD)

Today, perhaps the most common device for storing information. Hard drives can be internal (installed inside the case) and external (connected to the device using a USB cable). In the latter case, the hard drive has dimensions that allow you to carry it in your jacket pocket and connect it to almost any computer in a USB connector.

Each year, the cost per unit volume of stored information is reduced. Information is stored on plates inside a sealed container and coated with magnetic material. The recording technology is like a magnetic tape, and the device itself is like a floppy disk. The main difference is in the materials used. In addition, on the hard disk there is, firstly, electronics, which can fail, for example, from a power surge in the network, and secondly, high-precision mechanics. Due to the fact that during operation the read heads do not touch the surface of the disk, the surface does not wear out and can serve to store information for many years.

In case of careless handling (falling, shaking during operation), hard drives are subject to failure. So, one sharp shaking of a fully functional disk may be enough to lose all the information recorded on it without the possibility of recovery. With careful handling, the discs have been functioning properly for more than ten years with active everyday use. However, recently the quality of equipment leaves much to be desired, since in the pursuit of a low price, manufacturers are saving on equipment and materials.

Flash memory (flash memory), flash drives (flash drive)

Flash drives are storage media that use electrically erasable non-volatile memory for storage. If magnetic tape, floppy disks and hard drives were invented and widely used at the dawn of the development of computer technology, flash memory has become popular relatively recently. This is due to a breakthrough in chip technology.

There are both expensive solid state drives of large volume, and budget devices known as flash drives and memory cards. Today they are perhaps the most affordable and convenient means for everyday use. The memory card is a fully electronic device and can be connected to the device through a card reader. In contrast, flash drives do not require additional mechanisms for connecting to a computer.

The reliability of information storage declared by manufacturers is up to ten years. Unlike hard drives, flash drives are not afraid of shaking and falling from a small height. They are lightweight, roomy and have a high capacity, sufficient to record several films or tens of thousands of documents on one device.

With everyday use, flash drives quite often fail, for example, from static electricity, which destroys delicate electronics. The reason may also be in poor manufacturing and mistakes made by engineers when designing cheap devices, especially flash drives. The latter can fail due to damage to the microcontroller. In this case, information can theoretically be retrieved directly from a memory chip using special equipment. If the chip itself turned out to be damaged, then it is impossible to restore the data.

Technology does not stand still. And today, scientists are creating such media that for the inhabitants seem to be part of science fiction stories. However, when choosing a storage medium, one should be guided not only by fashionable technological trends, but also by common sense. If you need only a few mobile gigabytes of free space to store information (the size of a standard flash drive), then there is no point in buying expensive gigantic hard drives just to impress friends.

In addition, it is necessary to consider the costs of both the purchase of the medium itself and the costs associated with recording information and servicing equipment (for example, as in the case of film). In order to ensure reliable data safety, the optimal solution would be to choose not one but several storage media that can come to the aid of each other in case of annoying damage to one of the media.

Computer Science, Cybernetics and Programming

Storage of data information is not an independent phase in the information process but is part of the processing phase. There are structured data in which certain facts of the subject area are reflected: this is the main form of data presentation in the DBMS and unstructured arbitrary forms that include both texts and graphics and other data. This form of data presentation is widely used, for example, in Internet technologies, and the data itself is provided to the user in the form of a response by search engines. Organization of one or ...

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Question 2. Data storage.

Storage of information (data) is not an independent phase ininformation processbut is part of the processing phase. However, due to the importance of organizing storage, this material is placed in a separate section.

Distinguish structured datawhich reflects individual facts of the subject area (this is the main form of data presentation in the DBMS), andunstructuredarbitrary in form, including texts, graphics, and other data. This form of data presentation is widely used, for example, in Internet technologies, and the data itself is provided to the user in the form of a response by search engines.

The organization of this or that type of data storage (structured or unstructured) is associated with providing access to the data itself. Access refers to the ability to select a data element (or a set of elements) among other elements according to some criteria in order to perform some actions on the element. In this case, an element is understood as a file record (in the case of structured data), and the file itself (in the case of unstructured data).

For data of any kind, access is carried out using special data calledkey (keys ) For structured data, such keys are part of file records as separate record fields. For unstructured, search words or phrases are usually included in the search text. Using the keys, the required elements are identified in the information array (data storage array).

A further description of the information storage phase relates to structured data.

Models structured dataand technologies for their processing are based on one of three ways of organizing data storage: in the formlinear list (or tabular), hierarchical (or tree-like),networked.

Data storage- This is its record in auxiliary storage devices on various media for subsequent use.

Storage is one of the main operations carried out on information, and the main way to ensure its availability for a certain period of time.

The main content of the process of storing and accumulating information is to create, record, replenish and maintain information arrays and databases in an active state.

As a result of the implementation of such an algorithm, a document, regardless of the form of presentation, received in the information system, is processed and then sent to the repository (database), where it is placed on the appropriate "shelf" depending on the accepted storage system. The processing results are transferred to the catalog.

The information storage stage can be represented at the following levels:

External;

Conceptual, (logical);

Internal;

Physical.

External level reflects the information content and presents methods (types) of data presentation to the user during the implementation of their storage.

Conceptual the level determines the organization of information arrays and methods of storing information (files, arrays, distributed storage, concentrated, etc.).

Inner levelrepresents the organization of storage of information arrays in its processing system and is determined by the developer.

Physical levelstorage means the implementation of the storage of information on specific physical media.

The methods of organizing information storage are related to its search - an operation involving the extraction of stored information.

Storage and retrieval of information are not only operations on it, but also involve the use of methods for performing these operations. Information is stored so that it can be found for future use. The ability to search is laid during the organization of the memorization process. To do this, use methods of marking memorized information that provide search and subsequent access to it. These methods are used to work with files, graphic databases, etc.

Fig. one Algorithm for the process of preparing information for storage

Marker - a label on the information carrier indicating the beginning or end of the data or its part (block).

In modern storage media, markers are used:

Addresses (address marker) - a code or physical label on the track of the disk, indicating the beginning of the sector address;

Groups - a marker indicating the beginning or end of a data group;

Tracks (start of turnover) - a hole on the lower disk of a package of magnetic disks indicating the physical beginning of each track of the package.

Protections - a rectangular cut-out on a medium (cardboard package, envelope, magnetic disk) that allows performing any operations on data: writing, reading, updating, deleting, etc .;

End of file - a label used to indicate the end of reading the last record in a file;

Tape (tape marker) - a control record or physical label on magnetic tape, indicating the sign of the beginning or end of a data block or file;

A segment is a special label recorded on magnetic tape to separate one segment of a data set from another segment.

Information storage in a computer is connected both with the process of its arithmetic processing, and with the principles of organizing information arrays, searching, updating, presenting information, etc.

An important stage of the automated storage phase is the organization of information arrays.

Array - an ordered set of data.

Information array information storage system, including the presentation of data and the relationships between them, i.e. principles of their organization.

Information is stored on special media. Historically, the most common medium of information was paper, which, however, is unsuitable under ordinary (not special) conditions for long-term storage of information. For electronic computers, the following machine media are distinguished by the material of manufacture: paper, metal, plastic, combined, etc.

According to the principle of exposure and the possibility of structural changes, magnetic, semiconductor, dielectric, perforation, optical, etc. are distinguished.

By the method of reading distinguish contact, magnetic, electrical, optical. Of particular importance in the construction of information support are the characteristics of access to information recorded on the medium. Allocate direct and sequential access media. The suitability of the medium for storing information is evaluated by the following parameters: access time, memory capacity and recording density.

Thus, we can conclude that the storage of information represents the process of transmitting information over time, associated with ensuring the invariability of the state of the material medium.

Data storage

Information encoded using natural and formal languages, as well as information in the form of visual and sound images, is stored in the human memory. However, for long-term storage of information, its accumulation and transmission from generation to generation are usedinformation carriers.

The material nature of information carriers can be different: DNA molecules that store genetic information; paper on which texts and images are stored; magnetic tape on which sound information is stored; photo and film films on which graphic information is stored; memory chips, magnetic and laser disks on which programs and data are stored in a computer, and so on.

According to experts, the amount of information recorded on various media exceeds one exabyte per year (1018 byte / year). About 80% of all this information is stored digitally on magnetic and optical media, and only 20% is stored on analog media (paper, magnetic tapes, photo and film films). If all the information recorded in 2000 was distributed to all the inhabitants of the planet, then 250 MB would be required for each person, and for its storage 85 million 20 GB hard drives would be required.

Information capacity of storage media. Storage media are characterized by information capacity, that is, the amount of information that they can store. The most information-intensive are DNA molecules that are very small in size and tightly packed. This allows you to store a huge amount of information (up to 1021 bits in 1 cm 3 ), which allows the body to develop from a single cell containing all the necessary genetic information.

Modern memory chips allow you to store in 1 cm3 to 10 10 bits of information, however, it is 100 billion times less than in DNA. We can say that modern technology is significantly losing biological evolution.

However, if we compare the information capacity of traditional storage media (books) and modern computer storage media, then progress is obvious. Each floppy disk can hold a book of about 600 pages, and a hard disk or DVD contains a whole library of tens of thousands of books.

Reliability and durability of information storage. Of great importance is the reliability and durability of information storage. DNA molecules are more resistant to possible damage, since there is a mechanism for detecting damage to their structure (mutations) and self-healing.

Reliability (resistance to damage) is high enough for analog media, the damage of which leads to the loss of information only in the damaged area. The damaged part of the photo does not deprive the opportunity to see the rest, damage to the portion of the magnetic tape only leads to temporary loss of sound and so on.

Digital media is much more sensitive to damage, even the loss of one bit of data on a magnetic or optical disk can lead to the inability to read the file, that is, to the loss of a large amount of data. That is why it is necessary to follow the rules of operation and storage of digital storage media.

The most long-term carrier of information is a DNA molecule, which for tens of thousands of years (humans) and millions of years (some living organisms), retains the genetic information of this species.

Analogue media can store information for thousands of years (Egyptian papyrus and Sumerian clay tablets), hundreds of years (paper) and decades (magnetic tapes, photo and film).

Digital media has appeared relatively recently and therefore their durability can only be judged by expert estimates. According to expert estimates, with proper storage, optical media can store information for hundreds of years, and magnetic media for decades.

Storage and accumulation are one of the main actions carried out on information and the main means of ensuring its availability for a certain period of time. Currently, the determining direction of the implementation of this operation is the concept of a database, warehouse (warehouse) of data.

A database can be defined as a collection of interconnected data used by several users and stored with controlled redundancy. The stored data does not depend on user programs; a common control method is used to modify and make changes.

Databank - a system that provides certain services for storing and retrieving data to a specific group of users on a specific topic.

A database system is a combination of a control system, application software, a database, an operating system, and hardware that provides information services to users.

A data warehouse (CD - they also use the terms Data Warehouse, “data warehouse”, “information storage”) is a database that stores data aggregated over many dimensions. The main differences between the database and the database: data aggregation; data from the CD is never deleted; HD replenishment occurs on a periodic basis; the formation of new data aggregates depending on old ones is automatic; access to the CD is based on a multidimensional cube or hypercube.

An alternative to the data warehouse is the concept of data marts (Data Mart). Data marts - a lot of thematic databases containing information related to individual information aspects of the subject area.

Another important area of \u200b\u200bdatabase development is repositories. In a simplified form, the repository can be considered simply as a database designed to store not user, but system data. The technology of repositories stems from data dictionaries, which, as they enrich themselves with new functions and capabilities, have acquired the features of a tool for managing metadata.

Each of the participants in the action (user, user group, “physical memory”) has its own idea of \u200b\u200binformation

In relation to users, a three-level representation is used to describe the subject area: conceptual, logical and internal (physical).

Concept levelit is connected with the private presentation of user group data in the form of an external scheme, united by the commonality of the information used. Each specific user works with a part of the database and presents it as an external model. This level is characterized by the variety of models used (entity-relationship model, ER model, Chen model), binary and infological models, semantic networks).

Logic levelis a generalized representation of the data of all users in an abstract form. Three types of models are used: hierarchical, network, and relational.

The structure of basic information technology.

Define the structure and composition of typical IT. We will call typical ITthe base if it is focused on a specific area of \u200b\u200bapplication. Basic IT creates models, methods of solving problems. Basic IT is created on the basis of basic (standard) hardware and software. Basic IT is subordinated to the main goal - the solution of functional problems in its subject area (tasks of management, design, scientific experiment, testing, etc.).

At the input of basic IT as a system, a set of tasks is received, for which typical solutions must be found using the methods and tools inherent in IT. Consider the use of basic IT at the conceptual, logical and physical levels.

The conceptual level of basic IT - The ideology of automated problem solving is set. A typical sequence of problem solving can be represented in the form of an algorithm.

Fig. 2 . The conceptual model of basic IT.

The initial stage is the statement of the problem (PP). If this task is automated control, then it is a set of interconnected algorithms that provide control. PZ - a meaningful description of the problem: the purpose of the task, the economic and mathematical model and method of solving it, the functional and informational relationship with other tasks. It is documented in the teaching materials “Problem Statement and Solution Algorithm”. At this stage, the correctness of the description in terms of criteria is very important.

The next stage is the formalization of the problem (Federal Law). A mathematical model is being developed.

If the mathematical model is installed, the next step is the algorithmization of the problem (AZ). An algorithm is the process of converting source data to the desired result in a finite number of steps.

The implementation of the algorithm based on specific computing tools is carried out at the stage of programming the problem - PRZ. This is a voluminous task, but it is usually carried out using standard programming technologies.

If there is a program, a RH is carried out - solving problems - obtaining specific results for input data and accepted restrictions.

Stage AR - decision analysis. When analyzing the solution, you can refine the model of formalizing tasks.

The most complex, creative and voluminous are the stages of the formulation of the problem and its formalization. The concept of the initial task is a deep understanding of processes in the subject area.

In the context of basic IT, the global challenge is the development of a domain model (IGO).

When implementing IT, they often encounter poorly formalized tasks. Here expert systems come to the rescue. The basis of ES is laid the knowledge of the best experts in the subject area. An ES developer collects all known methods of formalizing this task. The user - the developer of this IT - receives options for solving problems. This is an IT design automation process.

The logical level of IT creation. Core IT Models

At a logical level, they establish models for solving the problem and organizing information processes. If the general management model of a certain ACS is known, into which basic IT will be implemented, we can imagine the interconnection of basic IT models.

The goal of basic IT at the logical level is to build a model of the problem to be solved and its implementation based on the organization of information processes.

Consider the relationship of basic IT models in the diagram.

Fig. 3 . The logical level of basic IT. A model for organizing information processes.

The model for solving the problem in the conditions of the selected basic IT is consistent with the model of organization of information processes (MOIP). MOIP includes MOD (data processing model), MO (data exchange model), MUPD (data management model), MND (data storage model), MPZ (knowledge representation model). Each of these models reflects certain information processes and contains the bases for constructing private matmodels of a specific information process.

Sharing model - estimates the probability-time characteristics of the exchange process taking into account routing (M), switching (K) and transmission (P) of information. The following are involved as impacts: input (message flows); interfering (error streams), and control (control streams). Based on this model, a data exchange system is synthesized, that is, they select the network technology, the method of optimal switching, routing.

MND data storage model.Defines the scheme of the information base of the NIB, establishes the logical organization of information arrays of AMI, sets the physical placement of information arrays of ROME.

Information array - the basic concept, the main element of the internal machine information support. IM - a collection of data on a group of homogeneous objects containing the same set of information. IM may include information:

oS programs and test programs (ensure computer operation);
application programs (provide a solution to a set of functional tasks);
library of standard programs.

Types of information arrays:

permanent (formed before the start of the system - directive, reference, regulatory data - not changeable over time);
intermediate (arise as a result of the previous calculation and the basis for the next);
current (contain working information about the state of the managed object);
service (serve the rest of the arrays);
auxiliary (occur during operations on the main arrays).

By type of carrier, IMs are divided into arrays on machine (internal and external) and non-machine carriers.

A specific feature of MI is its structure, a way of organizing data by key features. Records can be sorted in ascending or descending order by the value of a key attribute. The most common symptom is chosen as the key one.

MOD data processing model.It determines the organization of the computing processes of the ORP for solving user problems. The sequence and procedures for solving computational problems must be optimized in terms of criteria: memory size, resources, number of calls, etc. The organization of the process directly depends on the subject area. When developing basic IT, you should first choose the right OS. It is the OS that sets the real possibilities for managing the computing process.

The structure of the computing process is determined by the number of tasks. Very important are the requirements for the moment of launch and release (output of results) of tasks. These moments determine the dynamics of obtaining results, that is, the dynamics of the entire process of production management.

The first OS was focused on batch processing of information. This mode, in principle, is not suitable for control tasks of large dimension and efficiency. The transition to time-sharing systems made it possible to give priority to priority tasks under interruption conditions. It turned out to be possible to plan the computing process.

New features for the user are embedded in virtual OSs. It allowed the user to have an unlimited computing resource without noticing the work of neighboring users. In the conditions of distributed data processing, new requirements arise for the computing process. It is required not only to distribute the computing resource between users and their computing tasks, but also to take into account the topology of users.

When creating models for organizing a computing process (ORP), two possible approaches are used: deterministic and probabilistic. In the deterministic approach, the theory of scheduling the sequence of tasks under the imposed restrictions is applied. Unfortunately, random noise interferes with this convenient method. Unforeseen tasks may arise that require urgent solutions. Additional time intervals are allocated for them. With a probabilistic approach, it establishes the average computing resource, the average execution time of the program, and the average performance of the computing system. The averaged parameters are calculated based on statistical data and are constantly adjusted.

If we are inclined to typify the computational tasks to be solved for a particular IT, then the development of application software packages (PPP) is very important.

Among data processing models, simulation models should also be mentioned. With their help, the tasks of planning the organization of the computing process are solved.

The knowledge representation model of the MPZ.Representation models of knowledge are the basis for automated management tasks. Representation models of knowledge exist in the form of logical A, algorithmic A, semantic C, frame F and integral AND representations.

Data Management Model.Data management - management of the processes of accumulation, exchange and processing of data. The accumulation of data now takes place in the conditions of modern data bases, while the control action should be provided by the input of information, updating it, placing arrays in the database. These functions are performed by a modern DBMS.

With the advent of computers, data was accumulated as a set of identically constructed records - files. When solving each new task, new files were created. There was no logical connection between the files. There was a data integrity problem. A separate program was created for each file access. Individual data in the files were duplicated. The improvement of computer technology and the simultaneous growth of information volumes led to the emergence of the concept of databases. In the database, records are interconnected, can be shared to solve all new tasks.

Depending on the tasks to be solved, database models are selected.

Modern production solves a huge number of routine information tasks. But a very large number of tasks requiring information to make a decision. This requires new approaches to data formation, input and output, processing. These new approaches are being implemented with the help of new IT, realizing their mutual organization. This organization is in charge of a data management model. The model is based on the fact that the data are relatively stable. The stability of the data structure makes it possible to build databases with a stable structure. And the received information should be displayed in the form of variable data values \u200b\u200bin this stable structure.

In accordance with the domain model, a data class can be generated for all tasks to be solved. At the logical level, the subject database includes logical records, their elements and the relationship between them.

Network model it is a model of connection objects that allows only binary many-to-one relationships and uses a model of oriented graphs to describe it.

Hierarchical modelis a kind of network, which is a collection of trees (forest).

Relational modeluses the presentation of data in the form of tables (relations), it is based on the mathematical concept of a set-theoretic relationship, it is based on relational algebra and theory of relations.

Physical (internal) levelassociated with the method of actual storage of data in the physical memory of a computer. It is largely determined by the specific management method. The main components of the physical layer are stored records, combined in blocks; pointers needed to find data; overflow data; gaps between blocks; service information.

According to the most characteristic features of the database can be classified as follows:

by the method of information storage:

integrated;
distributed;

by user type:

single-user;
multi-user;

by the nature of the use of data:

applied;
subject matter.

Currently, there are two approaches to designing a database. The first of them is based on data stability, which provides the greatest flexibility and adaptability to the applications used. The application of this approach is advisable in cases where there are no stringent requirements on the efficiency of operation (memory size and duration of the search), there are a large number of diverse tasks with variable and unpredictable queries.

The second approach is based on the stability of the procedures for querying the database and is preferable under stringent requirements for operational efficiency, especially with regard to performance.

Another important aspect of database design is the problem of data integration and distribution. Until recently, the concept of data integration, with a sharp increase in its volume, prevailed until recently. This fact, as well as an increase in the amount of memory of external storage devices when they are cheaper, the widespread introduction of data networks contributed to the implementation of distributed databases. The distribution of data at the place of their use can be carried out in various ways:

The copied data. Identical copies of data are stored in various places of use, as it is cheaper than data transfer. Data modification is controlled centrally;
Subset of data. Data groups compatible with the source database are stored separately for local processing;
Reorganized data. Data in the system is integrated when transferred to a higher level;
Partitioned Data. Different objects use the same structures, but store different data;
Data with a separate subcircuit. Different objects use different data structures that are integrated into an integrated system;
Incompatible data. Independent databases designed without coordination, requiring consolidation.

An important influence on the process of creating a database is provided by the internal content of the information. There are two directions:

application databases focused on specific applications, for example, a database can be created to record and control the receipt of materials;
subject databases focused on a particular data class, for example, the subject database “Materials”, which can be used for various applications.

The concrete implementation of the database system is determined on the one hand by the specifics of the data of the subject area reflected in the conceptual model, and on the other hand, by the type of specific DBMS (MDB) that establishes the logical and physical organization.

To work with the database, a special generalized toolkit is used in the form of a DBMS (DBM), designed to manage the database and provide a user interface.

Main DBMS standards:

data independence at the conceptual, logical, physical levels;
universality (in relation to the conceptual and logical levels, type of computer);
compatibility, redundancy;
data security and integrity;
relevance and manageability.

There are two main areas of DBMS implementation: software and hardware.

A software implementation (hereinafter referred to as a DBMS) is a set of software modules that runs under the control of a specific OS and performs the following functions:

description of data at the conceptual and logical levels;
data loading;
data storage;
search and response to a request (transaction);
alteration;
ensuring security and integrity.

Provides the user with the following language tools:

data description language (YaD);
data manipulation language (NMD);
applied (built-in) data language (FAN, VND).

The hardware implementation involves the use of so-called database machines (MDBs). Their appearance is caused by increased volumes of information and access speed requirements. The word “machine” in the term MBD means an auxiliary peripheral processor. The term "database computer" is a stand-alone database processor or a processor that supports a DBMS.

The main directions of the MDB:

parallel processing;
distributed logic;
associative memory;
conveyor memory;
data filters, etc.

The set of database design procedures can be combined in four stages. On stageformulation and analysis of requirementsset the goals of the organization, determine the requirements for the database. These requirements are documented in a form that is accessible to the end user and the database designer. Usually, the method of interviewing personnel at various levels of management is used.

Stage conceptual designconsists in the description and synthesis of information requirements of users in the initial design of the database. The result of this step is a high-level presentation of user information requirements based on various approaches.

In the process logical designhigh-level data representation is transformed in the structure of the used DBMS. The resulting logical database structure can be quantified using various characteristics (the number of calls to logical records, the amount of data in each application, the total amount of data, etc.). Based on these assessments, the logical structure can be improved in order to achieve greater efficiency.

On stage physical designissues related to system performance are resolved, data storage structures and access methods are determined.

The entire database design process is iterative, with each stage being considered as a set of iterative procedures, as a result of which they get the corresponding model.

The interaction between the design stages and the vocabulary system needs to be considered separately. Design procedures can be used independently in the absence of a vocabulary system. The dictionary system itself can be considered as an element of design automation.

The stage of dividing the database is related to dividing it into sections and the synthesis of various applications based on the model. The main factors determining the partitioning technique are: the size of each section (permissible sizes); application usage patterns and frequencies; structural compatibility; database performance factors. The relationship between the database partition and applications is characterized by an application type identifier, a host identifier, the frequency of application use and its model.

Application models can be classified as follows:

Applications using a single file.
Applications that use multiple files, including:

Allowing independent parallel processing;

Allow synchronized processing.

The complexity of the implementation phase of the database is determined by multivariance. Therefore, in practice, it is recommended first of all to consider the possibility of using certain assumptions that simplify the functions of the DBMS, for example, the admissibility of temporary DB mismatch, the implementation of the database update procedure from one node, etc. Such assumptions have a great influence on the choice of the DBMS and the considered design phase.

Design tools and evaluation criteria are used at all stages of development. Any design method (analytical, heuristic, procedural) implemented in the form of a program becomes a design tool that is practically not affected by the design style.

Currently, the uncertainty in choosing criteria is the weakest point in database design. This is due to the difficulty of describing and identifying an infinite number of alternative solutions. It should be borne in mind that there are many signs of optimality that are immeasurable; it is difficult for them to quantify or present them as an objective function. Therefore, the evaluation criteria are usually divided into quantitative and qualitative. The most commonly used criteria for evaluating a database, grouped into such categories, are presented below.

Quantitative criteria: the time required to answer the question, the cost of modification, the cost of memory, the time to create, the cost of reorganization.

Qualitative criteria: flexibility, adaptability, accessibility for new users, compatibility with other systems, the ability to convert to another computing environment, the ability to restore, the possibility of distribution and expansion.

The difficulty in evaluating design decisions is also associated with different sensitivity and duration of the criteria. For example, the performance criterion is usually short-term and extremely sensitive to ongoing changes, and concepts such as adaptability and convertibility appear over long time intervals and are less sensitive to environmental influences.

The purpose of the data warehouse is information support for decision making, rather than operational data processing. Therefore, the database and the data warehouse are not the same concepts.

The main functions of the repositories:

on / off paradigm and some formal procedures for objects;
support for multiple versions of objects and configuration management procedures for objects;
notification of instrumental and working systems of events of interest to them;
context management and various ways of viewing repository objects;
definition of workflows.

Let us briefly consider the main directions of scientific research in the field of databases:

development of the theory of relational databases;
data modeling and development of specific models for various purposes;
mapping data models aimed at creating methods for their transformation and constructing commutative mappings, developing architectural aspects of mapping data models and specifications for determining mappings for specific data models;
creation of a DBMS with a multimodel external level, providing the ability to display widespread models;
development, selection and evaluation of access methods;
creation of self-describing databases that allow applying uniform access methods for data and metadata;
concurrent access management;
development of a database and knowledge programming system that would provide a single effective environment for both application development and data management;
improving the database machine;
development of deductive databases based on the use of mathematical logic and logical programming tools, as well as spatio-temporal databases;
integration of heterogeneous information resources.

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The concept that will be discussed is widespread in our everyday life. Information is a capacious word, refers to general scientific categories and is of great importance in different sciences.

The word itself came to us from the Latin language and in translation it sounds like awareness. In fact, this concept is abstract and has several meanings that depend specifically on something that determines the types of information. But nevertheless, the meaning of the word is that it is, first of all, a set of specific information stored and disseminated. And they, in turn, determine knowledge, which is always expressed in different forms. They surround a person always and everywhere, since without this the existence of life itself is impossible.

Various kinds of information are everywhere. We all know that only the apple tree and nothing more will grow from the seed of an apple tree. It is in a tree at the genetic level, and nothing can be changed. Air is a source of information for all trees (and not only): according to its state, trees can determine the time when you need to wake up to life. And take the Pack flies only a certain route, which is given in their genes, and it is not possible for them to turn off it.

In the modern world, this definition of presentation, method of storage and coding is divided into the following types of information:

Graphic (sometimes expressed by visual means);

Sound;

Text

Numeric

Video information.

The first specified type of information exists in drawings, paintings, photographs, diagrams, drawings. Known since the appearance of the first representatives of the future society. Sound information is expressed in sounds. This is also a rather ancient definition. Textual is a way of designating speech with symbols, that is, letters. Numerical is similar to it: encoding information using numbers. The latest invention in the modern world was video information - a way of storing and transmitting “live” pictures of the world. In addition to all the described types of information, there is also (sensations, smells, tastes, etc.)

All types of information require methods of storage and transmission, especially over long distances. At first, light signals were used for this, then radio waves. Since the advent of computers, storing and transmitting any information has become much easier. Information can be stored on various types of electronic media: magnetic disks, laser disks, special storage devices, such as flash cards. Every day there are new ways and devices. Any concept is processed without problems using a computer. Processing includes reproduction, transmission, conversion, recording of data. To do this, you only need to be able to use a computer and specially designed programs for such actions.

And, of course, the basic information of our time is presented on the world Internet. The methods of storage and transfer here are somewhat different from the usual and familiar to the person. Since its volumes on the Internet are very large, the ways to work with it are special. The software is being improved every day, which makes it possible to work with such information collectively and constantly.

Properties

Information, as we have said, is a specific object, and like all of them, it has certain properties that can be enumerated for a long time. Let us dwell only on the most important criteria. So, valuable and useful information in the first place should be:

Authentic;

Objective;

Topical;