Backup policy analysis for Windows servers (1)

◆ 1. Backup POLICY Overview

Original bkjia.com: What is the main difference between backup and replication? The answer is: Policy. In Windows, simple backup is actually not much different from replication. The real difference lies in the utilization of policies.

Copying a file to another disk is only a general backup, if you modify the original file before performing the backup, you must back up all the files again to achieve the backup effect. In addition, it is even more difficult to change large data volumes. For backup, various policies can be used to meet the needs of different environments.

For example, if my file is partially modified after the first backup, if you do not need to back up all the data, you can use the backup policy to back up only some of the modified data. Backup is basically a professional tool developed by various vendors or a Ntbackup tool provided by Windows.

From this we can see that the backup method that achieves the same redundancy data is far greater than the data backup Effect of replication. Next, we will introduce the classification of backup policies and their application in different environments.

◆ II. Backup policy type

In terms of backup policies, there are three common backup policies in Windows: regular backup, Incremental backup, and differential backup. The following describes the backup methods:

1. Regular backup:A regular backup is also called a full backup. If you do not check the mark before backing up the data, the backup will clear the mark.

2. Incremental Backup:A regular backup should be performed before the Incremental backup. The Incremental backup should check the mark before the backup data, and clear the mark after the backup. Incremental Backup only backs up data modified after the previous normal or Incremental backup.

For example, if some data is modified after the first regular backup, the backup will back up the data modified after the regular backup. If some incremental backups are performed afterwards, the data modified after the last Incremental backup is backed up again.

3. Differential backup:Similar to Incremental backup, a regular backup is required before the first differential backup. Check the mark before differential backup, but do not clear the mark after backup. Therefore, each backup will back up the data modified after the regular backup.

For the differences between the three backup types, see table 1-1 below.

Backup Type	Mark before backup	Mark after backup	Backup content
Regular/full backup	No	Yes	All data
Incremental Backup	Yes	Yes	Data modified since the last backup
Differential backup	Yes	No	Data after regular backup

Table 1-1

◆ III. Backup Policy

A good data backup tool requires a better policy to support it. If the backup policy is not used well, convenient Backup will be more than half the result.

There are three common backup policies: conventional backup, conventional backup + Incremental backup, and conventional backup + differential backup.

1. Regular backup:First, this backup policy is generally used only when data files are not too large and data changes are not frequent. If this policy is used, all backup data is completely backed up because the mark is not checked before the backup.

For example, if the conventional backup policy is adopted from Monday to Friday, all data will be backed up no matter how much data changes occur on that day. As shown in 3-1, all the changed data marked in red circles will be backed up at each backup.

Figure 3-1

Therefore, the advantage of this policy is that only the last data backup needs to be restored when data is recovered. The disadvantage is that it can only be applied to small files and data with less frequent changes.