The difference between "disaster recovery" and "backup" in a data center

Date: Oct 25, 2022

Related Tags：1. DCDN
2. Secure DCDN

Abstract: Disaster recovery system refers to the establishment of two or more sets of IT systems with the same functions in distant places, which can monitor health status and switch functions between each other. When a system stops due to an accident (such as fire, earthquake, etc.) When working, the entire application system can be switched to another place, so that the system function can continue to work normally.

Sudden failures in the operation of data centers (such as natural disasters and inevitable disasters) are unpredictable. The data in the computer is like a minesweeper game. Ambush is full of minefields, and there is a possibility of Game Over at any time. Disaster recovery is data security. The last line of defense, but you can avoid a data loss situation caused by data center failure and data loss.

Today, I will introduce the "difference between disaster recovery and backup" and some simple points to minimize the chance of failure and failure of operation and strengthen the data backup environment of enterprises.

What is disaster recovery?

Disaster recovery system refers to the establishment of two or more sets of IT systems with the same functions in different places far apart. Health status monitoring and function switching can be performed between each other. When a system stops due to an accident (such as fire, earthquake, etc.) When working, the entire application system can be switched to another place, so that the system function can continue to work normally.

Disaster recovery technology is an integral part of the high availability technology of the system. The disaster recovery system emphasizes dealing with the impact of the external environment on the system, especially the impact of catastrophic events on the entire IT node, and provides node-level system recovery functions.

Classification of disaster recovery

According to the degree of protection of the system, the disaster recovery system can be divided into: data disaster recovery and application disaster recovery. Data disaster recovery refers to the establishment of a remote data system, which is a real-time replication of local key application data.

Application disaster recovery is to establish a complete set of backup application systems (which can be mutual backups) in different places on the basis of data disaster recovery. Disaster is the guarantee against disaster, and application disaster recovery is the goal of disaster recovery system construction.

What is the connection between disaster recovery and backup?

Disaster recovery and backup are actually two concepts. Disaster recovery is to ensure the normal operation of information systems in the event of disasters and help enterprises achieve the goal of business continuity. Backup is to deal with data loss caused by disasters. Before the integrated disaster recovery and backup product appeared, the disaster recovery system and the backup system were independent. The ultimate goal of disaster recovery backup products is to help companies deal with "soft" disasters such as human error, software errors, virus intrusions, and "hard" disasters such as hardware failures and natural disasters.

The difference between disaster recovery and backup

In a general sense, backup refers to data backup or system backup, and disaster recovery refers to data backup or application system backup that is not in the same computer room. Backup is implemented by backup software technology, while disaster recovery is implemented by replication or mirroring software. The fundamental difference between the two is:

Disaster recovery is mainly aimed at major natural disasters such as fires and earthquakes. Therefore, a certain safety distance must be ensured between the backup center and the main center; data backup is performed in the same data center.

The disaster recovery system not only protects the data, but also ensures the continuity of the business; while the data backup system only protects the security of the data.

Disaster recovery ensures data integrity; backup can only restore data before the backup point in time.

Disaster recovery is an online process; backup is an offline process.

In the disaster recovery system, the data in the two places is consistent in real time; the backup data has a certain timeliness.

In case of failure, the switching time of the disaster recovery system is several seconds to several minutes; while the recovery time of the backup system may be several hours to dozens of hours.

Classification of disaster recovery

1. Data level

Data-level disaster recovery is the most basic method. It refers to the establishment of a remote disaster recovery center and remote backup of data. After a disaster occurs, it is necessary to ensure that the original data will not be lost or destroyed. However, at the level of data-level disaster recovery , the application will be interrupted in the event of a disaster. This disaster recovery method can be simply understood as a remote data backup center, which is to establish a data backup system or a disaster recovery system, such as databases, files, and so on.

Advantages: relatively low cost, relatively simple construction and implementation

Disadvantage: The recovery time for data-level disaster recovery is relatively long

2. Application level

Application-level disaster recovery is based on data-level disaster recovery. A set of identical application systems is also built at the backup site. Through synchronous or asynchronous replication technology, it can ensure that key applications can resume operation within the allowable time range, as far as possible. Reduce the losses caused by disasters, so that users basically do not feel the occurrence of disasters. Application-level disaster recovery is to establish a backup system for an application. For example, an OA system is running, and a set of the same OA system is established in another place.

Advantages: The service provided is complete, reliable and secure, ensuring business continuity

Disadvantages: higher cost, requires more software implementation

3, business level

Business-level disaster recovery is the disaster recovery of the whole business. In addition to the necessary IT-related technologies, it also requires all the infrastructure.

Pros: Guaranteed business continuity

Disadvantages: The cost is high, and the investment of the site cost is also required, and the implementation is difficult.

Backup level

Disaster recovery backup is to establish and maintain a backup storage system in different places, and use geographical separation to ensure the resilience of systems and data to catastrophic events. According to the degree of resistance of the disaster recovery system to disasters, it can be divided into data disaster recovery and application disaster recovery. Data disaster recovery refers to the establishment of a remote data system that replicates key application data of the local system in real time.

When a disaster occurs, the remote system can quickly take over the local system to ensure business continuity. Application disaster recovery has a higher level than data disaster recovery, that is, a complete backup application system equivalent to the local data system is established in different places (it can be mutually backup with the local application system, and can also work together with the local application system).

After a disaster occurs, the remote application system quickly takes over or undertakes the business operation of the local application system. To design a disaster recovery backup system, many factors need to be considered, such as the size of the backup/restore data, the difference between the application data center and the backup data center. According to these factors and different application occasions, disaster recovery backup can usually be divided into four levels.

Level 0: No Backup Center

This level of disaster recovery backup actually has no disaster recovery capability. It only backs up data locally, and the backed up data is only stored locally and not sent to other places.

Level 1: Local tape backup, offsite storage

Back up key data locally, and then send it to another place for storage. After a disaster occurs, restore the system and data according to the scheduled data recovery procedures. This solution is low cost and easy to configure. However, when the amount of data increases, the storage medium is difficult to manage, and when a disaster occurs, it is difficult to recover a large amount of data in time. To solve this problem, when a disaster occurs, restore critical data first, and then restore non-critical data.

Level 2: Hot Backup Site Backup

Establish a hot backup point in a different place, and perform data backup through the network. That is, the data of the primary site is backed up to the backup site in a synchronous or asynchronous manner through the network, and the backup site generally only backs up data and does not undertake business. In the event of a disaster, the backup site takes over the business of the primary site, thereby maintaining business continuity.

Level 3: Event Backup Center

Two data centers are established in distant places, and they are both in working condition and perform mutual data backup. When a disaster occurs in one data center, another data center takes over. This level of backup can be divided into two types according to the actual requirements and the amount of capital invested:

1. The two data centers are limited to mutual backup of key data;

2. The two data centers are mirror images of each other, that is, zero data loss, etc.

Zero data loss is currently the most demanding disaster recovery backup method. It requires the system to ensure data security no matter what disaster occurs. Therefore, it needs to configure complex management software and dedicated hardware devices, and the investment is relatively the largest, but so is the recovery speed.