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DOM 2010 Tape Backup (Data Written) seems low RRS feed

  • Question

  • Hello

    I have 4 protection groups. 1 protects 3 domain controllers, 1 protects my shoretel phone server, and the remaining 2 protect individual virtual servers each with several virtual machines. The backup policies are the same for all protection groups – except for the time of day the backups run.

    Short term backup to disk:

    -Short term recovery: 5 days

    -synchronization frequency “just before recovery point”

    -file recovery points and express full backup both run at the same time each day.

    Long term backup to tape:

    Recovery goal 1:

    Run every 1 day with 1 week retention

    Recovery goal 2:

    Run every week with 8 weeks retention

    Tape colocation enabled

    TapeWritePeriodRatio: 1

    ExpiryToleranceRange: 100

    (The above settings works nicely for me as it allows DPM to continue writing to a single tape until it is filled. The tapes then expire either 8 days or 8 weeks after the last backup to that tape. I like this arrangement as it works with my tape rotation schedule)

    All servers have the entire contents of their hard drives (C:\, D:\, etc.) bare metal recovery, and system state) protected.

    The issue seems that very little data is being written to tape. So far after 2 daily backups I have a total of only764,385 meg written to a single LTO5 tape. (600+ written day 1 and 100+ written day 2) It seems to me this is way too small. Just a single one of my domain controllers has a C:\ partition that is larger than this (even assuming 2 to 1 compression).

    Since I’m protecting physical servers and 12 virtual machines the data written to tape should be much larger than this. I was expecting hundreds of gigs not merely 700+ meg. My short term disk occupies about 1.8 TB. That is what i would have expected to see written to tape.

    I suspect that DPM is performing only an incremental type backup to tape. I don’t see a way to change that behavior. If I lost my short term disk based recovery (fire) how would I recover from these tapes? (I want a full back up on the tapes)

    I have read the KB article on how DPM uses tapes. My understanding is that it’s a full backup each time. That clearly can’t be the case with so little data being written to tape. (by the way I have no failed jobs and no alerts.)

    How do I make DPM do a full backup to tape EVERYTIME based on my retention goals.


    • Edited by ZackinMA Thursday, October 13, 2011 3:26 PM
    Thursday, October 13, 2011 3:21 PM

Answers

  • Hi,

     

    Check the job details for each data source that was backed up to tape.  The amount written should be very close to the amount used on the replica volume if you look at the details of the data source.    So as a test, simply right-click a large datasource, choose create recovery point, long term to tape, and see how much data gets written in the tape job details after it's completed.

    You are correct all long term backups are full backups, so the data written should closely match the replica space used for each data source. 


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Thursday, October 13, 2011 8:02 PM
    Moderator

All replies

  • Hi,

     

    Check the job details for each data source that was backed up to tape.  The amount written should be very close to the amount used on the replica volume if you look at the details of the data source.    So as a test, simply right-click a large datasource, choose create recovery point, long term to tape, and see how much data gets written in the tape job details after it's completed.

    You are correct all long term backups are full backups, so the data written should closely match the replica space used for each data source. 


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Thursday, October 13, 2011 8:02 PM
    Moderator
  • housekeeping - closing old post.  Open a new post if you still have a need.



    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Thursday, November 24, 2011 4:03 PM
    Moderator