When version 5 of Veeam Backup and Replication was released, many noticed that incremental mode for backup jobs is now the default. This may have caused some confusion to new customers as well as some that have not had much experience with Veeam Backup and Replication. Further, jobs created with version 4 retained their reversed incremental job mode.
Many have surely wondered why is this now the default job mode? There are number of reasons that this change was made. The foremost of which is that this format makes Veeam backups more ready to go to tape. The big difference is the transfer to tape, the previous jobs would change the archive bit on the large full backup file, the .VBK. The reverse incremental job modifies the .VBK file during each iteration. This means that if the .VBK file is to be transferred to a tape target, it would have to be transferred each time in its entirety due to the fact that the archive bit has been changed.
The archive bit behavior of the .VBK file is improved with the incremental mode. As it is not modified until the synthetic full iteration rolls previous incremental backups into the .VBK file. The new job mode’s default option is to include the synthetic full backups, also called forever-incremental. With this, there can be multiple .VBK files on disk. These may be large files, but a ripe candidate for data deduplication; should it be available on the storage target. If deduplication is not available, the .VBK files can consume quite a bit of space on disk and generally depends on retention configuration. A good way to represent this behavior is with a graphic, shown below.
The new incremental mode behavior rolls the prior job iteration .VIB files into the .VBK file during the synthetic full. At that point, the (new) .VBK file is modified and the archive bit will change for the file; which may effect the transfer to tape throughput. For those who are transferring to tape, this will save in transfers of the large .VBK file as the archive bit doesn’t change until the synthetic full operation. This is the default configuration, and it goes without saying that reviewing the User Guide for Veeam Backup and Replication v5 is a good idea for explanations of how this and the other backups modes operate.
These and other reasons are why this mode is now the default. Not to turn our ears to the community, user feedback for easier tape support is one of the drivers for making this the default as well. There are other features with incremental mode, such as being able to perform a restore concurrently while a backup is running because the backup files are no longer locked.
For disk only based backup jobs, it may be best to stick with the reverse incremental mode; which was the default in version 4 and for any upgraded jobs. How do you manage your job configuration with Veeam Backup and Replication v5 for job configuration? Share your comments below.