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consistency check - error + need clarification RRS feed

  • Question

  • Hello.

    Once again one of our BMR backups became inconsistent so I've ran consistency check, which failed ("The backup operation that started at '‎2010‎-‎07‎-‎19T10:18:29.831142600Z' has failed with following error code '2147943567' (The device is not connected.). Please review the event details for a solution, and then rerun the backup operation once the issue is resolved." in eventlog of the protected server, "DPM cannot create a backup because Windows Server Backup (WSB) on the protected computer encountered an error (WSB Event ID: 517, WSB Error Code:  0x8007048F). (ID 30229 Details: Internal error code: 0x809909FB)" in the DPM's alerts).

    Anyway I reran the consistency check once more and this time it seems to be working (still running while writing this post), but it had me wondering:

    1) when you run consistency check on inconsistent BMR (possibly system state too) backup, why does it transfer all the data again? I thought it's compare the changed blocks? Or is it because DPM for some reason can't tell that the data are 100% intact, so it essentially creates new FULL BMR backup?

    2) if 1) correct, does the same logic stand true for consistency checks of other resources (volumes, SQL DBs etc.)?

    3) if it really transfer the whole BMR backup again for every consistency check - is there any way to prevent this from happening since it creates HUGE network overhead when it needs to transfer the whole backup again (50GB in this specific case), which is not nice during production hours

    Details: DPM 2010 RTM Eval, protected resource: Windows 2008 R2 Standard

    Edit: ok, I was quick to say that consistency check works the second time - it failed again when it transferred ~26 out of 50GB with the same error (device is not connected) - what's the problem?

    Monday, July 19, 2010 11:01 AM

Answers

  • 1) Yes true, by default BMR backup is always a full backup if you consider the data being transferred over the network.

    2) No for aother applications like SQL and files only the changed data is transferred.

    3) Yes you can change the backups to happen just to transfer only the changes happened on the machine. But this has overhead of always keeping the last backups snapshot on the protected machine's volumes. This could slower the protected machines performance as low as 50%, hence full backup is preferred as transferring the data over network shouldn't caus much of a problem. If you want to configure this launch wbadmin.msc from an admin prompt on protected computer, in Actions pane click on Configure performance settings link. Then you can select the volumes and which way they need to backed-up full/incremental. You can give it a try in your environment and select the option to have a full backup vs incremental backup based how you find it doing in your environment.

    The backup failed because the replica/shadowcopy volumes for BMR backup are full. You need to allocate the disk space to succeed the next set of backups.

    Hope this answers all the questions raised above.


    Thanks, Praveen D [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Friday, July 23, 2010 9:42 AM

All replies

  • 1) Yes true, by default BMR backup is always a full backup if you consider the data being transferred over the network.

    2) No for aother applications like SQL and files only the changed data is transferred.

    3) Yes you can change the backups to happen just to transfer only the changes happened on the machine. But this has overhead of always keeping the last backups snapshot on the protected machine's volumes. This could slower the protected machines performance as low as 50%, hence full backup is preferred as transferring the data over network shouldn't caus much of a problem. If you want to configure this launch wbadmin.msc from an admin prompt on protected computer, in Actions pane click on Configure performance settings link. Then you can select the volumes and which way they need to backed-up full/incremental. You can give it a try in your environment and select the option to have a full backup vs incremental backup based how you find it doing in your environment.

    The backup failed because the replica/shadowcopy volumes for BMR backup are full. You need to allocate the disk space to succeed the next set of backups.

    Hope this answers all the questions raised above.


    Thanks, Praveen D [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Friday, July 23, 2010 9:42 AM
  • Thanks for the replies Praveen,

    quote: "The backup failed because the replica/shadowcopy volumes for BMR backup are full. You need to allocate the disk space to succeed the next set of backups." - the volumes are configured to auto-grow (and I'm not using custom volumes) - shouldn't volumes then be enlarged automatically without user intervention and/or raising alerts? At least that's how I understand that feature.

    Friday, July 23, 2010 11:16 AM