Exchange DAG client - default subclient not allowing multiple readers

Last post 08-29-2013, 11:06 AM by Mike2001. 8 replies.
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  • Exchange DAG client - default subclient not allowing multiple readers
    Posted: 11-10-2011, 3:20 PM

    I've noticed this problem at many customer sites over the last few months and I keep thinking it will be fixed in a patch but so far it seems to still be an issue.  I can't change the number of data readers from "1" on the default subclient for the Exchange DAG pseudo-client.  Even if I check the box "Allow mutliple readers for Backup Copy" and type in a larger number for the readers, it always reverts back to 1 reader.  This forces me to split out the databases into multiple subclients, which is fine but it gets tedious when dealing with dozens of databases.  Anyone know when this issue might be fixed so we can get multiple streams from the default subclient?

  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 11-10-2011, 3:28 PM

    i should first mention that this option is only for Backup Copy, i.e. snap backup movement to tape. this will not affect normal VSS backup operations.

    That being said, i cannot reproduce the issue on my 9.0 setup.  I can set the number of readers for backup copy to anything i want. I am not entirely sure if there is some sort of backend relationship to another property which could affect it however.

    can you let me know what is the max streams on your storage policy and the max number of writers on the library / mount path are ?


    Wearer of Many Hats
  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 11-10-2011, 3:43 PM

    Thanks, I did not realize that "Backup Copy" = "Snap Protect" for this subclient.  This is confusing terminology that I hope gets fixed in the GUI at some point.  In my case, I am not using Snap Protect, so this probably does not apply.  In the case of a regular DAG backup, using the default subclient, does it just use the maximum number of streams configured on the storage policy?  In my case I have 20 streams on my storage policy and 100 total device strams on my MagLib.  If there are 10 Exchange databases in the default subclient, will 10 streams be used automatically without needing to enter a value for data readers?

  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 11-10-2011, 3:45 PM

    Exchange Database backups (snap or non snap) are always single streamed.  Each subclient you have will use 1 stream regardless of how many databases you have configured in that subclient.

    This means that within a single subclient, each database configured as content will be backed up sequentially, not concurrently.


    Wearer of Many Hats
  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 11-10-2011, 3:57 PM

    Gotcha.  So it sounds like I will continue to need to break out each database into a dedicated subclient (i.e. 50 databases means 50 subclients) in order to get concurrent backup streams for Exchange.  Hopefully a future release will allow multi-streaming from a single subclient...

  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 11-10-2011, 8:43 PM

    We do one EDB per subclient and it works well.  It makes jobs run more quickly and simplifies management.  Our 2010 EDBs are 200 GB.  I can understand why this might be overkill for a smaller environment.

  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 08-29-2013, 10:31 AM

    Thanks for the information.

    we are using Exchange 2007 SP3.

    We are using Simpana version 9.0 R2.

    Dedup is "on client".

    On the Exchange mailbox server, in the Windows event logs, we see one database at a time.

    When SG1 gets done, SG2 starts, etc.

    Is this (single-threaded / one database at a time) still true for that environment ?

    Thanks.

    ==

  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 08-29-2013, 10:36 AM

    database backups are single threaded per subclient.  i.e. if you have 4 databases assigned to one subclient they will be processed sequentially.  if you have two databases in each of two subclients, the subclients will be processed in parallel, so two databases will be backed up at the same time. 

    if you have further questions, please start a new thread as this one is over 2 years old and already marked as resolved. 


    Wearer of Many Hats
  • Re: Exchange DAG client - default subclient not allowing multiple readers
    Posted: 08-29-2013, 11:06 AM

    Thanks for the quick reply.

    OK

    ==

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