SnapMirror relationships report "SnapMirrored" state before baseline is completed

Applies to

• ONTAP 9
• SnapMirror

Description

• SnapMirror relationships report a SnapMirrored Mirror state before they are completely done with the initial baseline replication transfer of all source volume data and Snapshots.
• For example, when initializing a source volume with 5TB used, the relationship reports a SnapMirrored Mirror State after moving just 27GB, as seen here in the snapmirror show command:

CLUSTERB::> snapmirror show
                                                                                                    Progress
Source                      Destination     Mirror         Relationship      Total                  Last
Path               Type     Path            State          Status            Progress    Healthy    Updated
-----------        ----     ------------    -------        --------------    ---------   -------    --------
svmprod:volprod    XDP      svmdr:voldr     Snapmirrored   Transferring      27GB        false      07/08 11:01:52

• In addition, the SnapMirror audit logs, located in /etc/log/snapmirror_audit on the destination controller, report a completed initialize operation with a smaller-than-expected bytes_transferred field.

Mon Jul 8 08:31:34 EDT 2019 Initialize[Jul 8 08:31:34]:01234567-0123-0123-0123-01234567890a Operation-Uuid=01234567-0123-0123-0123-01234567890a Group=none Operation-Cookie=0 action=Start source=svmprod:volprod destination=svmdr:voldr

Mon Jul 8 08:35:57 EDT 2019 Initialize[Jul 8 08:31:34]:01234567-0123-0123-0123-01234567890a Operation-Uuid=01234567-0123-0123-0123-01234567890a Group=none Operation-Cookie=0 action=End source=svmprod:volprod destination=svmdr:voldr status=Success bytes_transferred=26602694388 network_compression_ratio=1.0:1 transfer_desc=Logical Transfer with Storage Efficiency - Optimized Directory Mode Note=Scheduled update operation is queued.

• This is immediately followed by a ScheduledUpdate operation even if the relationship does not have a schedule defined.
  Mon Jul 8 08:35:57 EDT 2019 ScheduledUpdate[Jul 8 08:31:34]:01234567-0123-0123-0123-
01234567890a Operation-Uuid=01234567-0123-0123-0123-01234567890a Group=none OperationCookie=0 action=Start source=svmprod:volprod destination=svmdr:voldr 
• The ScheduledUpdate operation reports the remaining Snapshots to be transferred from the source.

Mon Jul 8 08:35:57 EDT 2019 ScheduledUpdate[Jul 8 08:31:34]:01234567-0123-0123-0123-
01234567890a Operation-Uuid=01234567-0123-0123-0123-01234567890a Group=none OperationCookie=0 action=Transfer_snapshots (1 of 1 log entries): daily.2019-07-07_0010,weekly.2019-07-07_0015,daily.2019-07-08_0010,hourly.2019-07-08_0305,hourly.2019-07-08_0405,hourly.2019-07-08_0505,hourly.2019-07-08_0605,hourly.2019-07-08_0705,hourly.2019-07-
08_0805,snapmirror.01234567-0123-0123-0123-01234567890a_0123456789.2019-07-08_083134

• This occurs on SnapMirror type-XDP relationships when they are using the MirrorAllSnapshots SnapMirror policy.
  • You can check the type of SnapMirror and the SnapMirror policy in use by running the command snapmirror show -fields type,policy 
  • This is the default relationship type and SnapMirror policy in ONTAP 9.3 and 9.4.
• SnapMirror type-XDP relationships using the MirrorAllSnapshots SnapMirror policy report a Snapmirrored Mirror State after successfully replicating the first Snapshot in the source volume.
  • The remaining Snapshots are transferred using a SnapMirror update operation, which is built into the initialize operation against these SnapMirror relationships.
  • The baseline of the source volume should not be considered complete until this update operation has ended successfully.