DELTA backup question



  • I have a question on the delta backups.

    If you set up a delta job on a new VM, it needs to take a full backup first, right?

    Can you still take a one-time full backup? How would that work? Would it break the chain?



  • The reason I ask is because I assume you would need a full backup before you could do a delta.

    But full does not show as a restore option when the job is set up as delta.



  • i assume that if you take a full backup, then you can create you vm by just this backup,



  • @alket said:

    i assume that if you take a full backup, then you can create you vm by just this backup,

    Right. I totally understand the full backup concept.

    My questions are ...

    1. If I have a new VM, and want to set up a delta-based backup ... do I have to run a full backup first? Or do I just set up a backup job of type delta?

    2. If I am running delta backups, and then do a separate full backup, what happens?



  • Reading the documentation will probably answer your question.

    You don't have to manually create the full-backup. The backup job will do it for you automatically.



  • @mk is right 👍 We manage that automatically.



  • @mk said:

    Reading the documentation will probably answer your question.

    You don't have to manually create the full-backup. The backup job will do it for you automatically.

    @mk can you point out to me where in that link it answers my question?



  • @olivierlambert said:

    @mk is right 👍 We manage that automatically.

    I actually played around with this on an empty NFS share, and saw this happen for myself, so yes. 🙂

    I also notivced that full backups are put in the root of the share, not a subdirectory. So does this mean for my other question that running a FULL backup does nothing to affect the delta chain?

    So say I have full backups existing ... will it use on of those for the delta chain, or will it take yet another full backup to start the delta chain?



  • You're kind of right, the documentation doesn't says it creates it automatically, but doesn't says that you should create it manually either. 😃

    The backup job usually creates a sub directory with the backup-type_tag_uuid naming schema for the machine and a sub directory for each connected VDI.

    I actually don't know. Never tried this, the developers should answer you this question or you try it out.



  • Full backups are not compatible with delta in any way. That's a complete different process.



  • @olivierlambert said:

    Full backups are not compatible with delta in any way. That's a complete different process.

    Got it.

    So it's like FULL-FULL and FULL-DELTA. 🙂



  • Nope, it's:

    • XVA/XVA/XVA (full backup using XenServer VM export mechanism)
    • or disk export + metadata, with full for each first disk backup, then delta and merge when retention is reached

    That's very very different


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