Always On: Backup on Secondary question

  • Hello all-

    I was hoping someone can shed some knowledge on Always On for me when it comes to back up on the secondary.

    The four options are:

    1. Only on the primary replica

    2. On secondary replicas

    3. Only on secondary replicas

    4. No preference

    I am testing always on and can't figure out how this part works. Here's what I did:

    - Chose option 2 (On secondary replicas)

    - Tried to take a manual full backup on the secondary

    - Receive an error that type backup isn't possible I can only take t-log backups on the secondaries

    So I chose option 4 instead and same issue.

    Can someone please help me understand how these options work? Seems like no matter which backup option I choose it will only let me do full\diff's on whichever server is considered the primary.

    Thank you for your time.

  • DBANoobie (1/30/2014)


    Hello all-

    I was hoping someone can shed some knowledge on Always On for me when it comes to back up on the secondary.

    The four options are:

    1. Only on the primary replica

    2. On secondary replicas

    3. Only on secondary replicas

    4. No preference

    I am testing always on and can't figure out how this part works. Here's what I did:

    - Chose option 2 (On secondary replicas)

    - Tried to take a manual full backup on the secondary

    - Receive an error that type backup isn't possible I can only take t-log backups on the secondaries

    So I chose option 4 instead and same issue.

    Can someone please help me understand how these options work? Seems like no matter which backup option I choose it will only let me do full\diff's on whichever server is considered the primary.

    Thank you for your time.

    Read Books Online (a WONDERFUL resource!!). In this section: Active Secondaries: Backup on Secondary Replicas (AlwaysOn Availability Groups) it states:

    Backup Types Supported on Secondary Replicas

    --------------------------------------------------------------------------------

    • BACKUP DATABASE supports only copy-only full backups of databases, files, or filegroups when it is executed on secondary replicas. Note that copy-only backups do not impact the log chain or clear the differential bitmap.

    Differential backups are not supported on secondary replicas.

    • BACKUP LOG supports only regular log backups (the COPY_ONLY option is not supported for log backups on secondary replicas).

    A consistent log chain is ensured across log backups taken on any of the replicas (primary or secondary), irrespective of their availability mode (synchronous-commit or asynchronous-commit).

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

  • Wow thank you so much for clarifying that with me sir, it is much appreciative.

  • And you cannot use Differential backups on secondaries.

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