Incremental backup and differential backup

Incremental backup)

Incremental backup is much faster than full backup. During Incremental backup, only files modified after the last full or Incremental Backup are backed up. For this reason, Incremental backup takes only a few minutes of full backup. To check whether a file is modified after the last full backup, the backup software checks a setting item called archive bit.

When a file is changed in any form or copied from one location to another, the Archive Bit records this change so that the file will be included in the next backup. Before full backup, you will not be concerned about whether the Archive Bit of these files has been set. However, the full backup will clear the Archive Bit after completion. Any files modified later will be recorded in the archive bit.

Differential backup does not clear the archive blocks after the backup is complete, while Incremental backup does, so that some files are backed up again without any need. Using an archive block also allows you to view the files that need to be backed up.

Faster backup also requires some cost-in this case, it is the recovery time. When recovering from an incremental backup, you need the latest full backup and all subsequent Incremental backup. For example, if you have performed a full backup on Friday, then Incremental backup is performed on Monday, Tuesday, or Wednesday, and the server crashes on Thursday morning, then, the user needs four tapes-a full backup box for Friday Incremental backup on Monday, Tuesday, and Wednesday.

Differential backup

Differential backup and Incremental Backup are often confusing, but there is a significant difference between them. Incremental Backup backs up the files that have been modified since the last full backup or after the Incremental backup. Differential backup backs up the files that have been modified since the last full backup. Recovery from differential backup is fast, because only two tapes are required-the last full backup and the last differential backup.

Differential backup is applicable to environments with sufficient space and time for backup. During differential backup, the software will find the files with archive blocks and then only back up these files.

As mentioned above, differential backup copies any files modified since the last full backup, while full backup clears the information in the archive block, and differential backup does not change the status of the archive block. The advantage of this is that only two tapes are needed for recovery. The disadvantage is that each differential backup is very likely