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How can i change data co-location maximum sources value or change "replica volumes" default size? RRS feed

  • Question

  • Hi,

    Is there any way to change this limit for data co-location sources?
    It's such a waste of disk space with some SQL instances which contain hundreds or thousands of small databases.

    The data co-location limit is set to 30 sources for default, and DPM creates automatically minimum 10GB of space for this "replica volume" and 18,41GB minimum for the "recovery point volume", regardless of the actual data size...
    If these 30 databases are 5-10MB each and we decide to keep that backup for, let's say 14 days with 1 recovery point per day.
    This means that we waste about 60-70% of free space for each of these 30 source containers. Well this doesn't sound as much, yet....but count those containers with 90 (per database instance)!
    Practically this means that we'll have to allocate 2,745TB disk space for one database instance which size is actually only 123GB. So, there are about 1TB empty space in that whole set which is nearly 1/3 of the allocated size.
    This just doesn't work when adding several this kinda database instances to DPM backup...

    So basicly, for this kinda data container where are small 5-10MB databases, we would actually need only like 1GB "replica volume" and about 10GB "recovery point volume", but DPM creates volumes that are over 2x larger that they should be...

    If we could push more databases into one container we would save all that "wasted" space, or if it'd be possible to change these containers minimum size limits automatically into smaller?
    Creating and counting these container sizes manually, one by one, is a huge waste of time.

    PS. We have many databases like this...so the waste of space is way too much.


    Kind Regards,

    Matti

     


    Thursday, November 3, 2011 11:24 AM

Answers

  •  

    Hi,

    We can co-locate up to 2000 small SQL databases to overcome the 300 limit data source limit (non-collocated limit).
    We allow up to 200 SQL DB’s / PG.
    We allow up to 30DB’s to be collocated on a single replica volume.

    The default SQL Co-located replica volume that DPM creates by default is 10GB meaning we will co-locate as many SQL databases that fit on that 10GB volume up to 30 before we create another 10GB volume.

    Depending on your average size database, you can modify that registry key so you can take better advantage of the co-location feature.

    The key is HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Data Protection Manager\Collocation\SQL
      Valuename= CollocatedReplicaSize and should be a multiple of 1GB  (1073741824 bytes decimal)

    Now, for you to do this, you would need to perform the following steps.

    1)  Calculate the average size SQL databases under protection, and plan for some growth over time.
    2) Multiply the (average size + growth) * 30 – this will be the new collocatedreplicaSize – make sure it’s a multiple of 1GB  (1073741824 bytes)
    3) Modify the registry key to make it that new value in decimal.
    4) Unprotect the  SQL databases and chose the option to delete the replica volumes (yes that will remove all your backups, but the only way to get them on co-located replicas) - be sure that you UNCHECK the option to delete tape recover points unless you want to expire them also.
    5) Re-protect the SQL databases, make sure the enable co-location checkbox is checked.
    6) DPM will make new replica volumes based on your value you specified and co-locate up to 30 DB’s per replica.

     


    Regards, Mike J. [MSFT] This posting is provided "AS IS" with no warranties, and confers no rights.
    Thursday, November 3, 2011 5:57 PM
    Moderator