Purpose
This article is intended to document how Forward Incremental works, and how its retention is enforced.
Solution
Forward Incremental Forever Backup Method – New in V8
Forward incremental-forever backup method is a default method for backup chain creation. To use this backup method, you must specify the following options in the backup job settings:
- Select the Incremental backup mode.
- Do not enable synthetic full backups and/or active full backups. If you enable synthetic and/or active full backups, Veeam Backup & Replication will produce a forward incremental backup chain (documented below).
The forward incremental-forever backup method produces a backup chain that consists of the first full backup and a set of forward incremental backups following it.
Veeam Backup & Replication creates a forward incremental-forever backup chain in the following way:
- During the first run of a backup job, Veeam Backup & Replication creates a full backup file (VBK) on the backup repository.
- During subsequent backup job sessions, Veeam Backup & Replication copies only VM data blocks that have changed since the last performed backup (full or incremental) and saves these blocks as an incremental backup file (VIB) in the backup chain.
Within this animation the lettered squares represent blocks on a disk.
Information regarding how retention works for this backup method can be found here:
https://helpcenter.veeam.com/docs/backup/vsphere/retention_forever_incremental.html?ver=95u4
Forward Incremental Backup Method
During the first run of a forward incremental backup, or simply incremental backup, Veeam Backup & Replication creates a full backup file (.vbk). During subsequent runs of the backup job, it will only retrieve changes that have taken place since the last run of the job (whether full or incremental) and saves this information as an incremental backup file (.vib). Each full backup files (.vbk) and its incremental files (.vib) that depend upon it are treated as a chain. Meaning that each incremental restore point depends on the one that came before it, the full restore point has no dependencies.
Within this animation the lettered squares represent blocks on a disk.
Incremental backup is the best choice if company regulation and policies require you to regularly move a created backup file to tape or a remote site. With incremental backup, you move only incremental changes, not the full backup file, which takes less time and requires less tape. You can initiate writing backups to tape or a remote site in Veeam Backup & Replication itself, by configuring Backup to Tape jobs.
If you decide to use the forward incremental backup method, it is necessary to schedule the creation of periodic active full or synthetic full backups. This will help you avoid long chains of increments, ensure safety of backup data, and allow you to meet the requirements of your retention policy. Below are animated examples of these things.
Within this animation the lettered squares represent blocks on a disk.
For more information please review the follow portions of the Help Center:
https://helpcenter.veeam.com/docs/backup/vsphere/incremental_forever_backup.html?ver=95u4
https://helpcenter.veeam.com/docs/backup/vsphere/retention_forever_incremental.html?ver=95u4
https://helpcenter.veeam.com/docs/backup/vsphere/forward_incremental_backup.html?ver=95u4
https://helpcenter.veeam.com/docs/backup/vsphere/retention_incremental.html?ver=95u4
https://helpcenter.veeam.com/docs/backup/vsphere/active_full_backup.html?ver=95u4
https://helpcenter.veeam.com/docs/backup/vsphere/backup_copy_remove_missing_point.html?ver=95u4