Media refresh questions - jobs spanning tapes and different library refresh

Last post 03-28-2019, 9:58 AM by drhooves. 4 replies.
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  • Media refresh questions - jobs spanning tapes and different library refresh
    Posted: 03-21-2019, 5:20 PM

    A couple of questions related to media refresh, in this case with LTO-5 tapes, single primary copy:

     

    1.  I freed up 500+ tapes running the process, but some tapes had read errors, and I had to "unpick" them to continue the job.  Since Commvault is job based tracking for data, does this mean all the data for a job that spanned multiple tapes is bad/lost?  Or can I catalog the volumes for a job OTHER than the bad one, and recover data for that portion of the job?

     

    2.  I have four sites with single tape drive libraries, and the main site has eight drives, all with unique bar code prefixes, and all using "Default Scratch" as the pool to create the transitive copies.  If I place 10 tapes with a different bar code range in the main site's library, how can I ensure the media refresh will pick up one of the two scratch volumes with that same VOLSER?  In other words, when scratch, the storage policy is no longer associated with the tape.  And I have my doubts that Commvault's media refresh will pick up on the "last library written in" flag.  I'd rather not create a global storage policy or define a uniquely named scratch pool, but if it comes to that, I'll do it.

     

    Thanks in advance.

  • Re: Media refresh questions - jobs spanning tapes and different library refresh
    Posted: 03-22-2019, 12:59 AM

    H drhooves

    In regards to your two questions:

    1. When Backup Jobs are spanned across multiple Tape, it really depends on the type of backup job. If it is a Database job, because the Database needs to be consistent, if you do have a bad tape then in most case you won't be able to restore successfully. If this is a Windows Backup there might be a chance that some data can be restored. 
    2. Base on the Tape selection process I would recommend using separate Scratch pool to control what tapes will be re-used first
     
    Regards
     
    Winston
  • Re: Media refresh questions - jobs spanning tapes and different library refresh
    Posted: 03-22-2019, 12:27 PM

    Hello Winston,

    Thank you for the responses.  I believe some of the jobs that span tapes are just backups of larger servers, like file shares, so if some of the data is possible to recover from the good tapes, that would be better outcome than losing the entire job.  Is the catalog feature the function used to read in the data from "good" tapes?

    As for the media refresh for tapes from other libraries, I did get steered in the right direction with your reponse, and created a temporary scratch pool for those tapes, updated the data path for the policy group, and was poised to watch it run....when I ran into the issue of the tapes in the main library use 6 characters, and the ones from the other single drive media agent's library use 8 characters.  <sigh>  So, instead of having 13 data and 2 scratch for the media refresh process, I had 15 scratch listed after importing them.  

    I don't recall trying to run a mixed set of 6 and 8 character tapes in the same library, so I may have to carve off a couple of drives and some slots for just this purpose.

    Regards,

    drhooves

     

     

     

  • Re: Media refresh questions - jobs spanning tapes and different library refresh
    Posted: 03-28-2019, 4:58 AM
    1. I freed up 500+ tapes running the process, but some tapes had read errors, and I had to "unpick" them to continue the job.  Since Commvault is job based tracking for data, does this mean all the data for a job that spanned multiple tapes is bad/lost?  Or can I catalog the volumes for a job OTHER than the bad one, and recover data for that portion of the job?

     

    You can set the DWORD registry MediaAgent/EnableLookAheadOffsetQueue to 0 on MA and run the restore job with “Skip errors and continue” option enabled in the Advanced Restore Options.

    This should help you restore the “good” data out of all the tapes that the job is written to.

    http://documentation.commvault.com/commvault/v11_sp14/article?p=62558.htm

     

    1. I have four sites with single tape drive libraries, and the main site has eight drives, all with unique bar code prefixes, and all using "Default Scratch" as the pool to create the transitive copies.  If I place 10 tapes with a different bar code range in the main site's library, how can I ensure the media refresh will pick up one of the two scratch volumes with that same VOLSER?  In other words, when scratch, the storage policy is no longer associated with the tape.  And I have my doubts that Commvault's media refresh will pick up on the "last library written in" flag.  I'd rather not create a global storage policy or define a uniquely named scratch pool, but if it comes to that, I'll do it.

     

    What we understood from the scenario is that there is data written on StandAlone libraries that need to be refreshed to a Main library on to a specific Barcode pattern.

    You can do the following:

    1. Create a new Spare Group on the Main Library.
    2. Configure the new Spare Group with the Barcode Pattern that is needed for Media Refresh(http://documentation.commvault.com/commvault/v11/article?p=10440.htm#o10442)
    3. Add the media with the selected barcode to the Library and when Discovered they will be moved to the Spare Group where the selected Barcode pattern was configured to.
    4. Add the Main Library Datapath with this new Spare Group as Scratch Pool to the storage policy copy on which Media Refresh needs to be run.

    After performing the above steps, the Media refresh job should pick the medias from the new Spare Group for writing.

  • Re: Media refresh questions - jobs spanning tapes and different library refresh
    Posted: 03-28-2019, 9:58 AM

    Hello Shivam,

    Thank you for the response and the details.  I'll go back and pick the bad tapes for refresh again, update the registry DWORD on the media agent, and see if that helps.

     

    As for the refresh of media in the main library, the definition of a new scratch group was the way to go.  After updating the storage policy used by the single drive library and adding a data path which used the new scratch pool, the process worked great.  I ran into a snag with the bar code length differences between the two libraries and worked around that, and when "cleared and aged" of data the last issue I had was the volumes from the single drive libraries returned to the "default_scratch" pool, and could have been used by the main library.  (although I believe there is an option to eject the media when refreshed).

     

    But the lesson I learned from this is that if you have multiple libraries, use standard bar code lengths and unique scratch pool names if you want to use media refresh at a different location.  Thanks!  Laughing

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