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Are "Data Written" Statistics Correct? RRS feed

  • Question

  •   I'm using LTO-4 media with DPM and am concerned that sometimes DPM shows "data written" as much as 2.4TB on one tape.

    That's not physically possible, is it?  LTO-4 holds 1.6TBcompressed.

    I've used every format of media over 20 years, and I am very familiar with the way various data structures compress compared to others, but I've never seen that much compression on any media format, no matter what the data structure, ever.

    I realize that DPM is writing a lot of metadata, file stubs, but is that being reported by DPM as the size of the file, rather than the size of the stub, which would greatly exaggerate the reported amound of data that went to the tape?

    Unfortunately I don't have 3TB of empty disk laying around that would allow me to restore all the data from a tape so I can confirm how much data gets restored and fill myself with confidence that all that data really is o nthe tape and accessible.  I have done many random recoveries and everything is there, but that is a hit-or-miss test and is does not fill me with confidence.

    The lack of job logs doesn't help either. 

    Thursday, June 28, 2012 7:14 AM

Answers

All replies

  • Hi,

    The easiest ways to see how much data was sent to tape is to download this utility and generate a report that shows how much data was written to tape.

    http://cid-b03306b628ab886f.office.live.com/self.aspx/.Public/DPMjobs-v3.0.zip?wa=wsignin1.0&sa=684718925 


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Thursday, June 28, 2012 8:54 PM
    Moderator
  •     DPM is reporting how much was written to tape on the management" tab under "libraries".

       I need to know how it can report 2.5TB written to a 1.6TB tape.  If a report shows a different amount than is reported on that management screen that's a big bug and we need to know about it.

      I don't have time to do the whole create a self signed certificate thing so I can run that report. 

    Tuesday, July 3, 2012 4:26 AM
  • Hi ,

    I don't get the "create self signed certificate" comment, there is no such requirement to run that DPMJobs utility.

    <snip>
     If a report shows a different amount than is reported on that management screen that's a big bug and we need to know about it.
    >snip<

    I agree, so please run the report and see the results to see if they differ.

    FYI - That DPMJobs utility was written before the last DPM QFE which changes the location of the custom filters, so if you are running DPM 2010 V3.0.8180, or DPM 2012 you must copy the JobFilters.xml file from the following directory before running the utility:

    Copy the JobFilters.xml from %SystemDrive%\Users\User name\appdata\Microsoft\Microsoft System Center Data Protection Manager TO DPMInstallLocation\DPM\bin folder anytime you modify or create a new filter so the utility can find it.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.


    Tuesday, July 3, 2012 2:15 PM
    Moderator
  •    The download at the link you posted above contains the info about all the certificate hoops that nee djumping in order to run the report.

       Can anyone get the info about the algorithm used to calculate the "data written" on the Libraries screen?

    Thursday, July 19, 2012 1:59 AM
  • Hi,

    Don't have clue what you are reading, but there are no certificates related to running the dpmjobs power shell script.

    There is no algorithm, dpm just keep track of bytes sent to that tape for all backup sets written. The dpmjobs script should calculate the same amount.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Thursday, July 19, 2012 2:59 AM
    Moderator
  •    When run from the shell, those scripts reply they are not digitally signed, and says to do "get-help about_signing" - that is where the jumping through the hoops is explained. 

       Can't anyone in development check the code and tell us if DPM is recording metadata/file stubs size as the size of the original file?  We have no confidence there is really 2.4TB of data on a LTO4 tape. 

      

    Thursday, August 9, 2012 3:04 AM
  • Hi,

    Please run two commands in the DPM power shell window prior to executing the script.

    set-executionpolicy remotesigned
    $confirmpreference = "None"

    That should prevent any prompts.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.

    Thursday, August 9, 2012 2:04 PM
    Moderator