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    Delta backups: Restore issue

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    Xen Orchestra
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    • M
      MrNaz
      last edited by

      Hi there,

      I have an XCP-ng host with a few VMs. Delta backups are set up to send their backups to a SMB remote. it appears to be working, jobs are reporting success. We have backups every 12 hours, with a full backup interval of 10.

      I am now trying to restore an old backup. When I try to restore one, however, I can only see the latest snapshot in the restore list. I cannot seem to select an older backup.

      How do I restore an older snapshot?

      1 Reply Last reply Reply Quote 0
      • A
        Andrew Top contributor @MrNaz
        last edited by

        @MrNaz It merges the past delta backup into the past full backup. Then it does a delta backup..... then you repeat.... Since you only keep one copy it just keeps merging the delta into the full backup. The delta backup depends on the old full backup existing and being correct.

        When it does a "full backup", it does a full backup of the data not just a delta (the changes). That way it does not merge the new full backup into the old full backup (or depend upon any old backups). Doing a full backup is a good checkpoint in case the old data (full or deltas) is corrupted.

        So having the retention set to 1 basically means you only have the most current backup saved. With backups every 12 hours you might want to set the retention to 20 so you have about 10 days of backups and every 5 days (10 backups) it will do a full backup. Or set it higher if you have more backup space.

        1 Reply Last reply Reply Quote 3
        • DanpD
          Danp Vates 🪐 Pro Support Team
          last edited by

          Take a look at your Backup Retention setting under the associated Schedule. What value do you see there?

          M 1 Reply Last reply Reply Quote 1
          • M
            MrNaz @Danp
            last edited by

            @Danp
            OMG it's set to 1.

            How does this setting interact with full backup interval? If it's only backing up the latest 1 backup, and a full backup was more than 1 backup run in the past, how is it possible to restore even the latest backup?

            A 1 Reply Last reply Reply Quote 0
            • A
              Andrew Top contributor @MrNaz
              last edited by

              @MrNaz It merges the past delta backup into the past full backup. Then it does a delta backup..... then you repeat.... Since you only keep one copy it just keeps merging the delta into the full backup. The delta backup depends on the old full backup existing and being correct.

              When it does a "full backup", it does a full backup of the data not just a delta (the changes). That way it does not merge the new full backup into the old full backup (or depend upon any old backups). Doing a full backup is a good checkpoint in case the old data (full or deltas) is corrupted.

              So having the retention set to 1 basically means you only have the most current backup saved. With backups every 12 hours you might want to set the retention to 20 so you have about 10 days of backups and every 5 days (10 backups) it will do a full backup. Or set it higher if you have more backup space.

              1 Reply Last reply Reply Quote 3
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