Understand how the retention policy works and how the quota of the backup storage is affected with Performance Cloud VMware (NSX-T)
TABLE OF CONTENTS
Description
Please review this article to understand how the retention policy works for Performance Cloud VMware and understand how the usage of the backup storage is affected and fluctuates.
Definitions
Incremental Backup
When an incremental backup job runs (also referenced as Forward Incremental Backup in Veeam documentation), it means that increments (changes since the last backup) are saved into new files dependent on previous files in the backup chain on your backup storage.
Synthetic Full Backup
When a synthetic full backup job runs, Veeam Backup & Replication consolidates backup data from the previous full backup file and the chain of subsequent incremental backup files on your backup storage and writes consolidated data into a new full backup file. Performing synthetic full backup jobs reset the backup chain. Any new subsequent incremental backup files use the latest synthetic full backup file as the new starting point.
For more details about (Forward) Incremental backup or Synthetic Full Backup, please review articles in the References section below.
Backup jobs
Performance Cloud VMware is integrated with Veeam Backup & Replication.
When a backup job is configured through the Performance Cloud VMware portal, a backup job is created in Veeam Backup & Replication in the backend.
Veeam Backup & Replication will then perform forward incremental backups according to the specified schedule and will also perform weekly synthetic full backups. This behavior cannot be changed.
Retention Policy details
Veeam Backup & Replication will keep more restore points in your backup storage than the number of restore points configured on backup jobs. This is absolutely normal to ensure a recovery according to the retention policy.
Without the full backup, a backup chain of forward incremental files would be completely useless. So, a previously used full backup file will be kept in your backup storage until it is automatically deleted according to the retention policy configured on backup jobs.
Example below with a backup job and a retention of ten (10) restore points in a daily schedule:
For the first ten (10) days, ten (10) recovery points exist in the backup storage.
Now, what happens on the eleventh (11th) day?
Will the first (1st) backup be deleted to keep the last ten (10) days?
The answer is No. As previously mentioned, all incremental backups in the chain depend on the full backup. The whole backup chain cannot be deleted for now. To ensure to keep ten (10) recovery points available for recovery, a new whole backup chain must be created.
Once ten (10) recovery points are secured, the previous whole backup chain will be deleted.
Throughout the days, the number of recovery points and the usage of your backup storage will continuously fluctuate.
You must keep enough free backup storage in your virtual data center to ensure backups are executing successfully. Especially when a whole backup chain must be kept for a certain time.
Having multiple backup jobs may affect your backup storage usage considerably.
Please pay attention to the usage of your backup storage and add necessary backup add-ons to your virtual data center through your account management portal Cumulus as needed.
References
https://helpcenter.veeam.com/docs/backup/vsphere/synthetic_full_backup.html?ver=120
https://helpcenter.veeam.com/docs/backup/vsphere/synthetic_full_hiw.html?ver=120
https://helpcenter.veeam.com/docs/backup/vsphere/retention_incremental.html?ver=120