What do users of modern information systems fear most? We will not conduct surveys and, based on them, compile a list of nightmares that torment them. We are simply stating that high on this grim list is the threat of data loss. And if the loss of data on a home computer in most cases is annoying, then the loss of information on a corporate network can be fatal for both the employee and the company as a whole. But for the one responsible for the backup, the fatality of this loss is absolutely inevitable. However, how fair is this?

Modern information systems problem Reserve copy is given top priority. Companies spend huge amounts of money on purchasing fault-tolerant disk arrays, specialized backup and storage devices, hire highly qualified professionals to maintain them - and still continue to lose data. Naturally, heads roll. However, the problem often lies in the misuse of perfectly debugged and configured systems. Figuratively speaking, users try to hammer nails with a microscope.

In February of this year, a terrible thing happened at a large publishing holding: data from one of the projects was lost. The following oddities were noted:

1. The project folder structure remained unchanged - only the files were missing.

2. No files were found on the backup tape (which, by the way, was performed daily), although the folder structure was fully present.

	Necessary measures to create a backup system A backup system is one of the necessary conditions for ensuring business continuity. According to Gartner, 43% of companies affected by disasters and experiencing a major permanent loss of corporate data were unable to continue operations. In order for the backup system to meet its purpose and operate optimally, it is necessary to complete a full cycle of design work, which, however, is recommended to be done for any system being created. The full cycle of work aimed at creating or upgrading a backup system usually includes the following stages: Technical audit of the computer system for the creation or modernization of a backup system; Development of the concept of a backup system - development of recommendations for the construction, modernization and development of a backup system. This type of work is not mandatory, but is recommended for large, dynamically developing systems; Design of a backup system - development of technical and working documentation; Development of a schedule for the transition from the old backup system to the new one. This type of work is necessary when upgrading the backup system, which has led to a significant change in the existing system; Supply and configuration of equipment and software; Development of operating procedures - organization of operating processes for the backup system, development of regulations and schedules for the backup system. This type of work is very important: without a properly organized operation process, not a single system, including the backup system, will work effectively; Drawing up a training program for customer personnel on data backup and recovery. For a backup system, personnel training plays a special role. Since the purpose of the backup system is to restore data after failures, the personnel carrying out this procedure will work in an emergency situation and lack of time to restore the system’s functionality. Consequently, the execution of data recovery operations should be brought to automaticity by administrators, which can only be achieved through regular practice.

The investigation, traditionally for Russia, went in two directions: identifying those responsible and taking measures to eliminate the possibility of a similar situation repeating in the future.

First of all, complaints were made about the backup software. The reason why this was done turned out to be very prosaic: it is the backup software that must pass through the entire disk structure to copy information to tape, and therefore, in the event of any malfunction, it is theoretically capable of destroying files. Since this assumption came from the victims, simply stating that this was impossible was clearly not enough. Leaving aside the possibility of such a unique glitch occurring in a certified and legally purchased software product, we were forced to find a simple and clear way to convince non-specialists of the absurdity of this assumption. This task is extremely difficult (and in most cases impossible), but we succeeded. The fact is that the backup software uses one of the domain accounts when working with files; therefore, it is limited in its destructive capabilities by the rights of the account being used. By default, the local administrator account is used, which allows full access to all information stored on the server. On the one hand, this approach is justified by the fact that it eliminates the situation when backup cannot be performed due to lack of access rights to the backup information. On the other hand, administrator rights imply full access, allowing you to delete information. In the situation under consideration, the backup software worked under a specially created account, having access to all information, but without the ability to change it (read-only access). It was this fact that allowed the IT department to prove that the backup software was not involved in the incident.

Thus, after the cessation of the panic that arose, an attempt was made to comprehend what had happened and find its most acceptable explanation. First of all, it was established that three months before the moment in question, the lost project folder was empty. This fact was reflected in the backup software operation protocols and was included in the case. It was then determined that the server contained a completed project that had not been accessed for at least three months. As a result, after information was deleted from the server, it was stored on tapes for a month (the period of rotation of magnetic media in the backup scheme used), after which the tapes were overwritten, and this information was finally lost.

	Backup system requirements Since any modern Information system is built on the basis of a network, the backup system must also be network-based, that is, it must ensure the preservation of data coming from all network nodes. In general, the following functional requirements are put forward for a network backup system: Building a system based on the “client-server” principle. When applied to backup, the client-server terminology means the following: the component of the backup system that manages all processes and devices is called the server, and the component responsible for saving or restoring specific data is called the client. In particular, such a system should provide: Management of backups throughout the entire network from dedicated computers; Remote backup of data contained on servers and workstations; Centralized use of backup devices. Multiplatform. Modern information network is heterogeneous. Accordingly, the backup system must fully function in such a network, that is, it is assumed that its server part will work in various operating environments and support clients on a variety of hardware and software platforms. Automation of typical operations. The backup process inevitably involves many cycles of different operations. For example, copying can occur every day at a certain time. Another example of a cycle is the process of overwriting information on backup media. If daily backup copy should be stored for a week, then after this period the corresponding media can be used again. This process of sequentially replacing backup media is called rotation. Cyclic work also includes preventive maintenance of backup devices, for example, cleaning the components of the tape drive mechanism of the tape drive using a special cassette after a certain period of operation. Thus, the backup system should perform cyclic work automatically and minimize the number of manual operations. In particular, it must support: Perform scheduled backups; Media rotation; Scheduled maintenance of backup devices. It should be noted that automation of work is one of the key conditions for reducing the cost of maintaining a backup system. Support various backup modes. Let's say that every day you need to back up a certain set of files, such as those contained in the same directory. As a rule, changes are made only to individual files during the working day, as a result of which daily copying of information that has remained unchanged since the previous backup was created is unnecessary. Based on this, the system must provide various backup modes, that is, support the ability to save only the information that has been changed since the creation of the previous copy. Quick recovery of network servers after a disaster. A network server may fail for various reasons, for example due to a system crash hard drive or due to software errors leading to the destruction of system information. In this case, its restoration requires reinstalling the OS, configuring devices, installing applications, restoring file system and user accounts. All these operations are very labor-intensive, and errors may occur at any stage of this process. Thus, to restore a server, it is necessary to have a backup copy of all information stored on it, including system data, in order to bring it back to working condition as quickly as possible. Data backup in interactive (on-line) mode. Often, an information system includes various client-server applications that must function around the clock. Examples of this are email systems, collaboration systems (eg Lotus Notes) and SQL servers. It is impossible to back up the databases of such systems using conventional means, since they are open all the time. Therefore, they often have their own backup tools built in, but their use, as a rule, does not fit into the overall technology adopted by the organization. Based on this, the backup system must ensure that client-server application databases are saved online. Advanced monitoring and management tools. To manage backup processes and monitor their status, the backup system must have graphical monitoring and control tools and a wide range of event notification tools.

So, we have established the chronology of information loss. Now we are faced with a very difficult task - to identify those responsible. On the one hand, the backup system failed to cope with the task of saving information. On the other hand, this information was stored on tapes for a month and could be restored at the user’s first request. But this demand was not received, because the project was completed and no one was working with it. As a result, everyone is right, there are no guilty people, and there is no information. The current situation is a good example of the wrong use of the right technology. Let's answer the question: what is the task facing backup systems? The priority task is to quickly and completely restore information in the event of a failure. Another thing is that in the example under consideration, the fact of the failure was not tracked - and, accordingly, data recovery was not performed. But this cannot in any way be blamed on the administration and backup service.

The situation under consideration is an example that clearly demonstrates the need to maintain at least a two-level backup system - daily backup of current information and separate backup of rarely used information (in our case, completed projects). Unfortunately, the need for such an approach to the problem of information security, as a rule, does not find understanding among management.

How did this sad story end? Here's what:

1. It was decided to save completed projects on DVD.

2. The rotation period of magnetic media has been increased to three months.

3. A policy for storing and reserving information was developed and adopted throughout the holding.

P.S. The data was nevertheless found in one of the file deposits, of which there are many on any network.

Backup systems ensure the continuity of business processes and the protection of information from natural and man-made disasters and the actions of intruders. These technologies are actively used in the IT infrastructures of organizations of various industries and sizes.

Data backup- the process of creating a copy of data on a medium designed to restore data to its original location in the event of damage or destruction. In addition, a backup system is one of the necessary methods to ensure business continuity. Building a centralized backup system allows you to reduce the total cost of ownership of your IT infrastructure due to the optimal use of backup devices and reduced administration costs (compared to a decentralized system).

Organizational difficulties regarding data protection

• Internal contradictions in the technical team
• Should application administrators be responsible for data integrity, SLAs, and recovery?
• Centralized automated control – reducing risks for the IT director: increasing transparency and predictability of IT processes

The right data protection strategy for the data center

Legacy approach called "BACKUP"

• Backup
• Recovery

A modern approach called “INFORMATION MANAGEMENT”

• Backup
• Recovery
• Content Analytics
• Contextual search
• Mobile data access
• Seamless cloud integration
• Information security tasks
• ANY third-party data processing applications (Open API)

Copy problem

• Without a centralized approach, the amount of data grows uncontrollably
• Where is the most current version data?
• If I need to delete Compliance data, where can I find all copies?
• Removing and archiving outdated information. How to determine a reasonable criterion for the value of data?

Architecture and operation of the backup system

The centralized backup system has a multi-level architecture, which includes:

• a backup management server that can also combine the functions of a data copy server;
• one or more data copy servers to which backup devices are connected;
• client computers with backup agent programs installed on them;
• backup system administrator console.

The system administrator maintains a list of backup client computers, recording devices and storage media for backup data, and also creates a backup schedule. All this information is contained in a special database, which is stored on the backup management server.

In accordance with the schedule or at the command of the operator, the management server instructs the agent program installed on the client computer to begin backing up data in accordance with the selected policy. The agent program collects and transmits data to be backed up to the copy server specified to it by the management server.

Off-server copying

This type of backup is a further development of the off-network copying method (LAN-free), since it reduces the number of processors, memory, and I/O devices involved in this process. This process archives entire partitions, as opposed to file-by-file archiving, but at the same time allows you to restore individual files. By definition, off-server copying copies data from disk to tape and back without direct involvement of the server. Since backup requires the presence of some additional third node, which is fully responsible for the copying process, this is where another name for this approach comes from - copying with the participation of a third party (Third_-Party Copy, 3PC). So, a data storage router can be used as such equipment, which takes over the functions previously performed by the server.

One of the advantages of the SAN architecture is the absence of a rigid connection of its component systems to any data storage devices. This property is the basis of server-less backup technology. In this case, both the data server and the devices that take part in copying from the disk arrays can have direct access to the disk array. Backing up data blocks related to a file is preceded by the creation of a certain index or list of block numbers belonging to it. This allows you to use external devices for backup in the future.

Thus, off-server copying allows you to directly move data between SAN-connected disk arrays and libraries. In this case, the data moves over the SAN network and does not load any local network, nor servers. Such copying is considered ideal for corporate networks that must operate continuously 24 hours a day, 7 days a week. Especially for those for which the time period in which backups can be performed without significantly impacting the user and application experience becomes unacceptably short.

Data replication

Modern disk arrays have the means to create copies of data within the array itself. The data created by these tools is called Point-In-Time (PIT) copies, i.e. fixed at a certain point in time. There are two types of means of creating PIT copies: cloning and snapshot. Cloning usually means a complete copy of data. It requires the same amount of disk space as the original data and some time. When using such a copy, there is no load on the disk volumes containing the original data. In other words, there is no additional load on the disk subsystem of the productive server.

The mechanism of operation of “snapshots” is different and can be implemented both programmatically on a productive server and in hardware inside the array. At the moment when it is necessary to start a backup, the agent program instructs the application to complete all transactions and save the cache memory to

Backup Software.

Purchasing suitable equipment is a necessary, but not sufficient condition for building a backup infrastructure. Another important part of the problem isselection of specialized software that will serve as a logical basis for protecting data from destruction.

If you need to back up a single user's files, standard utilities such as Ntbackup on Windows or tar on Unix systems are usually sufficient. They can be used to set the backup method and determine whether files have changed (required when performing selective backups), but their use across the entire enterprise does not seem appropriate.

For small companies, you can often do without special software at all. For backup with the minimum required functionality, it is supplied with the OS (this statement is true for both MS Windows and UNIX), and with the Oracle DBMS, for example, a truncated version of Legato Networker is supplied.

Medium and large companies need to have a well-organized backup infrastructure with high degrees of integration and automation; they have to purchase specialized software with a client-server architecture.

When with corporate information systems the situation becomes significantly more complicated. They include a large number of different computers that use special technologies: file servers, database servers, and the like. Backing up information on them requires special technological solutions. In addition, for corporate information systems it is important not only to preserve user information, but also to restore the functionality of computers and servers as quickly as possible in the event of any, even hardware failures. This allows you to avoid long downtime for employees and associated company losses.

It is obvious that for the successful operation of the entire backup complex it is necessary coordinated work of both software and hardware. Therefore, for enterprise-scale backup systems standard means backups are not applied. There are several important requirements that data backup and recovery software for large enterprises must satisfy:
- Building a system based on the client-server principle. Since any modern information system is based on a network, the backup system must also be network-based. Such a system should provide: backup management throughout the entire network from dedicated computers; remote backup of data contained on servers and workstations; centralized use of backup devices. When applied to backup, client-server terminology means the following: the component of the backup system that provides control of all processes and devices is called the server, and the component responsible for saving or restoring specific data is called the client. An enterprise-scale backup software product must ensure the coordinated operation of all elements of a computer network - workstations, servers and backup devices - to ensure the least load on devices and communication channels. To do this, the following organization of the software package is used: system server, management console (in general, not installed on the server), backup agents (client programs installed on workstations). In addition, such a product must provide the ability to work with clients managed by different operating systems. Finally, such programs must provide access to user and database files, even if those files are open and in use by the system.
- Multiplatform. The modern information network is heterogeneous. Accordingly, the backup system must fully function in such a network, i.e. it is assumed that its server part will work in various operating environments and support clients on a variety of hardware and software platforms. Availability, at a minimum, of clients for different operating systems.
- Automation of typical operations. The backup process inevitably involves many cycles of different operations. The backup system should perform cyclic work automatically and minimize the number of manual operations. In particular, it must support: scheduled backups, media rotation, scheduled maintenance of backup devices. For example, copying can occur every day at a certain time. Another example of a cycle is the process of overwriting information on backup media. If the daily backup is to be kept for a week, then after this period the corresponding media can be used again. This process of sequentially replacing backup media is called rotation. Cyclic work also includes preventive maintenance of backup devices, for example, cleaning the components of the tape drive mechanism of the tape drive after a certain period of operation using a special cassette. It should be noted that automation of work is one of the key factors in reducing the cost of maintaining a backup system.
- Supports various backup modes. Let's say that every day you need to back up a certain set of files, such as those contained in the same directory. As a rule, changes are made only to individual files during the working day, and daily copying of information that has remained unchanged since the previous backup was created is unnecessary. Based on this, the system must provide various backup modes, i.e., support the ability to save only the information that has been changed since the previous copy was created.
- Easy installation, support for a wide range of drives, quick recovery of network servers after a disaster. A network server can fail for various reasons, for example due to a system hard drive failure or due to software errors that lead to the destruction of system information. In this case, restoring it requires reinstalling the OS, configuring devices, installing applications, restoring the file system and user accounts. All these operations are very labor-intensive, and errors may occur at any stage of this process. Thus, to restore a server, it is necessary to have a backup copy of all information stored on it, including system data, in order to bring it back to working condition as quickly as possible.
-Availability of modules for major DBMS (MS-SQL, Oracle, DB/2) and business-critical applications (MS Exchange, SAP R/3, etc.); online data backup. Often, an information system includes various client-server applications that must function around the clock. Examples of this are email systems, collaboration systems (for example, Lotus Notes) and SQL servers. It is impossible to back up the databases of such systems using conventional means, since they are open all the time. Therefore, they often have their own backup tools built in, but their use, as a rule, does not fit into the overall technology adopted by the organization. Based on this, the backup system must ensure that client-server application databases are saved online.
- Possibility of both central and local administration, developed monitoring and management tools. To manage backup processes and monitor their status, the backup system must have graphical monitoring and control tools and a wide range of event notification tools, and a function for generating and distributing reports.
Based on the requirements above, enterprise backup software must be superior to an SMB (Small/Medium Business) solution. However, it also requires significantly higher acquisition costs, as well as training costs. For this reason, when choosing a product, you should consider the advanced and additional features and technologies it supports. For small existing solutions that can no longer be scaled up due to new requirements, all leading vendors offer software upgrades to enterprise-class products, and disk backup is considered particularly important features for large enterprises, as they significantly improve backup performance and provide additional features data protection.

Popular solutions for the corporate sector are HP Data Protector, Bakbone NetVault, BrightStor ARCserve Backup (Computer Associates), Legato NetWorker, Veritas NetBackup and some others. Many of these products are deservedly popular in Russia. All of them are designed to work in heterogeneous environments with different types of operating systems and large volumes of data and meet high requirements for performance, stability and availability. Therefore, support for storage area networks is a mandatory component of these products. Through multiplexing, enterprise backup solutions provide high performance, support multiple libraries and drives, and can be tailored to specific needs using database agents and operating systems. The type of software in question is a set of additional features that either come with the storage system or are available from third-party vendors. These typically include: creating volume snapshots (snapshots), creating a full working copy of a volume (snapclone), scheduled data replication (replication), and volume-level data mirroring to remote storage (synchronous/asynchronous mirroring).

Manufacturers of data storage systems (DSS) and storage software offer several concepts for solving this problem. This functionality can be present in the form of controller microcode (Hitachi), as an additional server module (appliance) (EMC, HP, IBM), or at the FC switch level (Cisco, Troika).

The manufacturers of Brand A data warehouses listed above zealously make sure that this functionality only works between “their own” ones, i.e. members of the same family of models. At the same time, solutions available from Cisco and Troika make virtualization transparent for any storage and are universal. However, it should be noted that both approaches are very cheap to implement and are not available to every organization.

You should also dwell on the features of choosing programs for performing archiving procedures. As with backup software, the choice of archiving software is determined by the individual needs and requirements of the business. Selection and implementation are carried out taking into account the business processes affected and the relevant legal requirements. An important point is the correct approach to the archived data sets, since often the application or type of information being archived determines the required software. The following most important selection criteria are generally recognized:
- taking into account legal aspects and legislative requirements;
- a full-fledged search system for the information array;
- ability to work with the required application;
- performance during archiving, searching and evaluation;
- support for necessary devices;
- integration into a complete storage solution.

Since most archiving software is application specific, some companies offer specialized solutions for classic email and ERP systems. Major manufacturers of systems for SAP include Open Text (SAP Document Access and SAP Archiving applications), IBM (DB2 CommonStore for SAP), EMC (Archive Services for SAP), Technoserv AS (Technoserv Content Server) and some others with their products for content and document management, and archiving. Integrated solutions that support archiving and information lifecycle management of structured and unstructured data from various applications will become the most rational option in the future, as they can reduce administration costs. HP Reference Information Storage System (RISS) already supports Microsoft Exchange and Outlook, Lotus Domino and documents in file formats of MS Office applications, Adobe PDF, HTML and others.

The future evolution of backup and archiving software is driven by the trend of device virtualization, which will enable flexible resource sharing, broader and more comprehensive application support, and the development of high-performance search capabilities. In addition, a number of developments are aimed at improving compatibility between backup and archiving software, such as shared media management. In the long term, the boundaries will become even more blurred - perhaps both storage disciplines separately will no longer exist.

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Most often, the current system resources are not enough to perform backup procedures. And, often, you have to spend a lot of effort to justify the need to purchase additional hardware to implement the reservation procedure. Indeed, from the point of view of an ordinary user, such a situation may be unlikely and insignificant. However, it cannot be ignored.

Thus, it is necessary to initially determine the list of the most important tasks that the system will have to carry out in order to store data as efficiently as possible. To this end, it is necessary to answer a number of questions, thanks to which it will be possible to determine a number of basic necessary characteristics.

The first thing to determine is how important the data being stored is. If the data can be restored by re-downloading or re-creating, then backup operations can be performed less frequently. In case the data is very important, a more reliable backup strategy must be adopted.

The next important factor is the frequency of changes to the data. The more often the data changes, the more often the backup operation needs to be performed.

In this case, it is necessary to calculate the required amount of disk space. After all, the volumes are affected by the number of copies that must be simultaneously stored in the system.

In the case of a deployed heterogeneous enterprise information infrastructure, it may be necessary to separate information into types with different redundancy requirements.

There are several types of backup. These are full backup, differential backup, incremental backup.

A full backup is the main and fundamental method of creating backup copies, in which the selected data array is copied in its entirety. This is the most complete and reliable type of backup, although it is the most expensive. If it is necessary to save several copies of data, the total stored volume will increase in proportion to their number. To prevent a large amount of resources used, compression algorithms are used, as well as a combination of this method with other types of backup: incremental or differential. And, of course, a full backup is indispensable when you need to prepare a backup copy for quickly restoring the system from scratch.

This method has both its advantages and disadvantages. The main advantage is the ease of restoration from scratch. Since the array is completely saved, it is also not difficult to restore only part of the necessary data. One of the disadvantages is the redundancy of this method. During operation, many files may remain unchanged, however, they will also be included in the backup copy. Thus, a fairly large volume of media will be required. Not only does a full backup take up unnecessary storage space, it can also be time-consuming, especially if you have network-attached storage.

An incremental backup, unlike a full backup, does not copy all data, but only those that have changed since the last backup. Various methods can be used to determine the backup time, for example, on systems running Windows operating systems, a corresponding file attribute (archive bit) is used, which is set when the file has been modified and reset by the backup program. Other systems may use the date the file was modified. It is clear that a scheme using this type of backup will be incomplete if a full backup is not carried out from time to time. When performing a full system recovery, you need to restore from the latest copy, and then one by one restore data from incremental copies in the order in which they were created. This type is used to reduce the amount of space consumed on information storage devices when creating archival copies. This will also minimize the execution time of backup jobs, which can be extremely important when the platform is constantly running. Incremental copying has one caveat: step-by-step recovery also returns unnecessary deleted files during the recovery period. Therefore, when sequentially restoring data from an archive, it makes sense to reserve more disk space so that deleted files can also fit.

One of the advantages of the method is the effective use of media. Because only files that have changed since the last full or incremental backup are saved, backups take up less space. Correspondingly, shorter backup and recovery times. Incremental backups take less time than full and differential backups.

The disadvantage of this method is that the backup data is stored on multiple media. Since backups are located on multiple media, restoring a device after a disaster may take longer. Additionally, to effectively restore the system, the media must be processed in the correct order.

Differential backup differs from incremental backup in that data is copied from the last moment a full backup was performed. The data is stored in the archive on a “cumulative basis”. On Windows family systems, this effect is achieved by the fact that the archive bit is not reset during differential copying, so the changed data ends up in the archive copy until a full copy resets the archive bits. Due to the fact that each new copy created in this way contains data from the previous one, this is more convenient for completely restoring data at the time of the disaster. To do this, you only need two copies: the full one and the last of the differential ones, so you can return lost data much faster than restoring all increments step by step. In addition, this type of copying is free from the above-mentioned features of incremental copying, when during a full recovery old files are restored unnecessarily. At this method Fewer inconsistencies occur. But differential copying is significantly inferior to incremental copying in saving the required space. Since each new copy stores data from previous ones, the total volume of reserved data can be comparable to a full copy. The disadvantage of this method, as when creating a full backup copy, is excessive data protection. All files changed since the last incremental backup are preserved.

In the process of backing up data, the problem of choosing a technology for storing backup copies and data arises. Currently, the most common types of media are: magnetic tape drives; network technologies; disk drives.

The most common type of disk drives: magnetic hard disk drives.

Hard magnetic disk drives are the main devices for operational storage of information. Regarding the server case, a distinction is made between internal and external drives. Internal drives are significantly cheaper, but their maximum number is limited by the number of free compartments in the case, the power and the number of corresponding connectors of the server's power supply. Internal drives with hot swap (HotSwap) are ordinary hard drives installed in special cassettes with connectors. Cassettes are usually inserted into special compartments on the side of the front panel of the case; the design allows the drives to be removed and inserted while the server is powered on. External drives have their own cases and power supplies; their maximum number is determined by the capabilities of the interface. Maintenance of external drives can also be performed while the server is running, although it may require stopping access to some of the server’s drives.

For large volumes of stored data, external storage units are used - disk arrays and racks, which are complex devices with their own intelligent controllers that, in addition to normal operating modes, provide diagnostics and testing of their drives. More complex and reliable storage devices are RAID arrays (Redundant Array of Inexpensive Disks - a redundant array of inexpensive disks). For the user, RAID is a single disk in which simultaneous distributed redundant writing (reading) of data is performed on several physical drives (typically 4–5) according to rules determined by the implementation level (0–10).

The advantages of such drives are fast access to data and the possibility of parallel access to data without a significant loss of speed. Disadvantages include a fairly high cost, higher power consumption, more expensive expansion of the data storage system, and the inability to ensure high security of copies.

There is also the option of storing backup data on network storage. By and large, information will be stored on the same disk drives, only in remote storage. The only difference is that communication with him will be carried out through network technologies. The main advantage is the ease of connecting additional platforms for data storage and the need for them to be located in close proximity to the servers on which the data to be copied is located. Additionally, it is possible to set any Raid level of the array in the network storage itself, thereby providing flexibility in choosing the security level for stored data. In some cases, you don’t even have to purchase additional equipment, but place information on rented sites. The price will be significantly lower than when purchasing equipment for storing data arrays. The only inconvenience with such data placement is the low, in some cases, access speed. And the need to reserve a communication line to access the storage.

One of the cheapest (if you calculate the cost of a drive per 1 GB of data) methods of storing information is to use tape drives. Robotic tape libraries have come a long way in recent years. Like modular disk arrays, such libraries provide flexible and, most importantly, cost-effective expansion of system capacity as the volume of data that needs to be stored on tape grows, high reliability, and also have powerful tools remote control and monitoring. Even the largest libraries have limits on the number of tape cartridge slots, but if all the tape cartridges in the library are full, some of the old backups can be sent to storage and new cartridges installed in their place. For disk arrays, this option of “unlimited” scaling is impossible, if only because hard disks They are much more expensive than cartridges and are not intended for long-term storage in a disconnected state. The main disadvantage similar systems storage can be considered the presence of a mechanical part for accessing the required tape cartridge. The second, quite noticeable, but not critical minus is the speed of copying to tape. It is significantly lower than in disk arrays. But a way out of this situation was quickly found. Libraries are equipped with disk arrays and initially the necessary data is written off to it, and then transferred to magnetic tape, without in any way interfering with the operation of the system.

As mentioned above, backup alone is not enough. A set of measures is needed to prevent emergency situations. All components of the backup infrastructure must be considered in the planning process, and all applications, servers, and trends in primary storage capacity must not be ignored.

Reviewing error logs and backup progress is a necessary daily task. Backup problems tend to happen in an avalanche. A single failure can lead to a whole sequence of seemingly unrelated difficulties. For example, a backup job may either hang or fail to start because the required tape drive was not freed by a previous job. Such situations require immediate intervention and adjustment of the backup process in order to avoid future problems with the lack of necessary copies.

All backup applications maintain their own database or directory, which is necessary for subsequent recovery of saved data. Loss of the directory results in loss of saved data. Although some backup applications have mechanisms to correctly read tapes and indexes for recovery, this can be an overwhelming task. Such a directory should be treated like any other mission-critical database application. It is advisable to have a mirror copy of it or at least store it in a RAID system. In addition, it is advisable to ensure that the directory is saved according to schedule and without errors. Database corruption can also cause unwanted data loss.

Also in real systems the data needs to be differentiated. The person responsible for backup must clearly understand how the system works and distinguish between data types. As stated above, some data can be backed up less frequently, while others need to be backed up more often. Scheduling and frequency of copying is one of the most important tasks. But, even taking into account the diversity of data, the system should be as automated and centralized as possible.

Another important procedure is checking the created copies for reading. Indeed, sometimes backups, for one reason or another, may not be readable. And it is advisable to discover this fact not at the moment when you need a copy for recovery.

Thus, a clearly developed and planned backup planning strategy will be able to completely eliminate and prevent the occurrence of emergency situations and data loss, thereby ensuring the full and uninterrupted functioning of the enterprise’s information infrastructure.

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Protecting data (which includes installed software) from deletion or corruption is not an easy task even in the absence of deliberate actions on the part of attackers. As a rule, to solve it it is necessary to use a set of software and technical measures, the main of which are:

data backup;

thoughtful configuration and maintenance of the required (“safe”) values ​​of system parameters;

advance installation and mastery of specialized data recovery software.

The listed measures must be provided for at the stage of developing the organization's security policy and reflected in the relevant regulatory documents (in the security policy document, in private instructions of structural units and in the job responsibilities of performers).

Data backup

Backup can be considered a panacea in almost all situations involving data loss or corruption. However, backup will only prove to be a truly universal “cure” if you follow the rules for its use. Features of restoring various types of data based on backup copies will be given in the relevant chapters of the section now Let's look at the general principles of backup.

Archiving and Backup

These two concepts are so often used together in publications and when working with data that they sometimes even begin to be perceived as synonyms. In fact, although archiving (the English term archiving) and backup are great “friends,” they are not twins or “relatives” at all.

What is the meaning behind each of these terms?

Archiving very close to the creation of non-computer, “paper” archives. An archive is a place adapted for storing documents that have either lost their relevance or are used relatively rarely.

Documents in the archive are usually ordered (by dates, logic, authorship, etc.). This allows you to quickly find the document you are interested in, correctly add a new document or delete an unnecessary one.

Almost all of the above features are also inherent in electronic archives. Moreover, the leading role in their creation is played by the ability of archiving programs to compress the archived data, thereby saving space for their storage. It was this ability of archivers that made them friends with backup programs, but more on this a little later.

Target Reserve copy on a computer - to increase the reliability of storing those data, the loss of which may upset (to put it mildly) their owner. For particularly valuable data, two or more backup copies can be created. As a rule, when backing up you have to solve two interrelated problems : what data to copy, and how often. On the one hand, the more often you copy, the less effort you will have to spend on restoring a document lost, for example, due to a hard drive failure. On the other hand, creating each new copy requires time and storage space. In many cases, it is the use of compression methods implemented in archiving programs that allows you to select the appropriate parameters for the backup procedure. Essential difference between backup and archiving is that at least one backup copy must be created not on the hard drive storing the original, but on an alternative medium (CD, etc.).

Another difference between archiving and backup given below.

You can create an archive, including rarely used data, and save it either directly on your computer’s hard drive or (preferably, but not necessarily) on another medium. And after that good luckupload source files (originals).

Procedure backup requires the obligatory preservation of the original(that is, the data with which the user works). Backup is intended primarily to improve safety of data that continues to be used in operation (that is, they change periodically). That's why backups should also be done periodicallyski update. In this case, the use of additional storage media (storage devices) is mandatory. Ideally, each copy should be stored on a separate medium.