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Problem with differential restore

Scheduled Pinned Locked Moved Backup
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  • F
    frank-s
    last edited by 3 Oct 2024, 13:54

    When I try to perform a differential restore I get this error:
    VDI_INCOMPATIBLE_TYPE(OpaqueRef:94df0a4b-69ba-4ef5-adb3-21c5259ea0b1, CBT metadata)
    Regular restore appears to be working.
    Any advice please?

    1 Reply Last reply Reply Quote 0
    • O
      olivierlambert Vates 🪐 Co-Founder CEO
      last edited by 3 Oct 2024, 14:31

      Hi,

      Can you describe exactly what are you doing in the UI, using what XO, which version and so on.

      F 1 Reply Last reply 3 Oct 2024, 14:53 Reply Quote 0
      • F
        frank-s @olivierlambert
        last edited by 3 Oct 2024, 14:53

        @olivierlambert
        I am using XO from the sources.
        commit a9b99 Master, commit 30172
        When I try to restore I select the appropriate backup (I have done this with both internal NFS remote and also with s3 remote). I select the SR that the backed up VM is on and turn on "use differential restore". When I click OK it fails immediately with the following error: <VDI_INCOMPATIBLE_TYPE(OpaqueRef:6ef1574a-ffc6-412b-bf6b-6804bacc0523, CBT metadata)>
        This also happens on a completely different installation (different XCP different XO different client).
        It's been a while since I used differential restore. It seems odd that when turned on I can select any destination SR. My understanding is that the restore needs the same SR as the original VM - that's what I selected.
        When I last used differential restore I was not using NBD/CBT.
        Regular restore seems to be working.

        20ae3ebd-3801-485c-8b59-9193e06c2c56-image.png

        Thanks,
        Frank.

        1 Reply Last reply Reply Quote 0
        • olivierlambertO
          olivierlambert Vates 🪐 Co-Founder CEO
          last edited by 3 Oct 2024, 14:57

          Thanks, it's a lot more clear now 🙂 I don't think diff restore works with CBT as we remove the snapshot data. But it's a good question so we update the UI to reflect that and/or document it. @florent will confirm

          1 Reply Last reply Reply Quote 0
          • F
            frank-s
            last edited by 3 Oct 2024, 15:07

            So my guess is it will work if I choose not to delete the snapshot??? If that is correct it is a pity as differential restore is very fast compared to regular restore. Differential restore, for instance, would be a brilliant way to recover quickly from a ransomware attack. Also, deleting the snapshot makes coalescing much faster. Am I correct in my assumptions? Is there a way it could be made to work without the snapshot?
            Thank you,
            Frank.

            florentF 1 Reply Last reply 3 Oct 2024, 15:18 Reply Quote 0
            • olivierlambertO
              olivierlambert Vates 🪐 Co-Founder CEO
              last edited by 3 Oct 2024, 15:08

              I have the impression it's one or another, to choose between pro and cons on the two.

              1 Reply Last reply Reply Quote 0
              • F
                frank-s
                last edited by 3 Oct 2024, 15:10

                I will backup again without deleting the snapshot and then attempt a differential restore.
                I will update this thread when done.

                1 Reply Last reply Reply Quote 1
                • florentF
                  florent Vates 🪐 XO Team @frank-s
                  last edited by 3 Oct 2024, 15:18

                  @frank-s said in Problem with differential restore:

                  So my guess is it will work if I choose not to delete the snapshot??? If that is correct it is a pity as differential restore is very fast compared to regular restore. Differential restore, for instance, would be a brilliant way to recover quickly from a ransomware attack. Also, deleting the snapshot makes coalescing much faster. Am I correct in my assumptions? Is there a way it could be made to work without the snapshot?
                  Thank you,
                  Frank.

                  differential restore work by not transferring the data that the snapshot and the backup have in common, without reading any of those
                  it clone the last snapshot, an then revert the block changed between the older backup and the snapshot.

                  In theory, if you run a delta backup without destroying the data, it should provide the anchor to have this work.

                  F 1 Reply Last reply 3 Oct 2024, 15:56 Reply Quote 0
                  • F
                    frank-s @florent
                    last edited by 3 Oct 2024, 15:56

                    @florent
                    I just did a delta backup on a small VM but chose NOT to delete the snapshot. It completed quickly and I then tried a differential restore and it worked. I also tried to do a differential restore on a delta backup made yesterday when the snapshot was deleted - this also worked. Will it be possible in the future to make differential backups work without keeping the snapshot? Is such a thing possible?
                    Thanks,
                    Frank.

                    F 1 Reply Last reply 3 Oct 2024, 16:26 Reply Quote 0
                    • F
                      frank-s @frank-s
                      last edited by 3 Oct 2024, 16:26

                      @frank-s Soz - I meant differential restores...

                      1 Reply Last reply Reply Quote 0
                      • olivierlambertO
                        olivierlambert Vates 🪐 Co-Founder CEO
                        last edited by 3 Oct 2024, 17:21

                        You can't have CBT/flush snap + diff restore. In your case, our future instant restore feature might be one you seek.

                        1 Reply Last reply Reply Quote 0
                        • F
                          frank-s
                          last edited by 3 Oct 2024, 17:24

                          Thank you. Is there somewhere I can read about this instant restore feature?

                          1 Reply Last reply Reply Quote 0
                          • olivierlambertO
                            olivierlambert Vates 🪐 Co-Founder CEO
                            last edited by 3 Oct 2024, 17:26

                            No, because it's a planned feature. In short, XOA will act as an temporary SR so you can instantly start the backup VM, then migrate it to the target storage.

                            K 1 Reply Last reply 17 Oct 2024, 18:00 Reply Quote 0
                            • F
                              frank-s
                              last edited by 3 Oct 2024, 17:27

                              Thank you.

                              F 1 Reply Last reply 16 Oct 2024, 14:53 Reply Quote 0
                              • F
                                frank-s @frank-s
                                last edited by 16 Oct 2024, 14:53

                                @frank-s So- I have been thinking about this. If an NBT/CBT backup is set to destroy the snapshot, would it be possible to make differential restore work by having the restore process create the snapshot it needs, perform the differential restore and then delete the snapshot?

                                1 Reply Last reply Reply Quote 0
                                • olivierlambertO
                                  olivierlambert Vates 🪐 Co-Founder CEO
                                  last edited by 16 Oct 2024, 14:58

                                  Recreating the snapshot from the CBT metadata? The problem is the CBT metadata doesn't make sense alone, only compared to the data saved by XO. So this will need to read a lot of data between XO and the host, not sure it will be faster at all (probably the opposite)

                                  F 1 Reply Last reply 16 Oct 2024, 15:51 Reply Quote 0
                                  • F
                                    frank-s @olivierlambert
                                    last edited by 16 Oct 2024, 15:51

                                    @olivierlambert No, not recreating the snapshot from the CBT metadata but simply creating a new temporary snapshot, perform differential restore and delete the temporary snapshot when done.

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                                    • olivierlambertO
                                      olivierlambert Vates 🪐 Co-Founder CEO
                                      last edited by olivierlambert 16 Oct 2024, 15:55

                                      I'm not sure to follow. You need a point of reference in time to restore. If you start from a new snapshot, and apply the diff blocks (from XO backup) on top of it, it will be complete nonsense.

                                      F 1 Reply Last reply 16 Oct 2024, 16:52 Reply Quote 0
                                      • F
                                        frank-s @olivierlambert
                                        last edited by 16 Oct 2024, 16:52

                                        @olivierlambert So, earlier in this thread, florent said "differential restore work by not transferring the data that the snapshot and the backup have in common, without reading any of those
                                        it clone the last snapshot, an then revert the block changed between the older backup and the snapshot". If this is true (and I'm sure it is) why can't the differential restore system create the missing snapshot and use that to complete the differential restore?

                                        1 Reply Last reply Reply Quote 0
                                        • olivierlambertO
                                          olivierlambert Vates 🪐 Co-Founder CEO
                                          last edited by olivierlambert 16 Oct 2024, 18:37

                                          That's true as long as you keep the snapshot data, which is not the case in NBD+purge data.

                                          F 1 Reply Last reply 16 Oct 2024, 22:21 Reply Quote 0
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