SnapMirror preserves storage efficiency on the source and destination volumes except when postprocess data compression is enabled on the destination volume. In that case, all storage efficiency is lost on the destination volume. To correct this issue, you need to disable postprocess compression on the destination volume, update the relationship manually, and re-enable storage efficiency.

About this task

You can use the volume efficiency show command to determine whether efficiency is enabled on a volume. Learn more about volume efficiency show in the ONTAP command reference.

You can check if SnapMirror is maintaining storage efficiency by viewing the SnapMirror audit logs and locating the transfer description. If the transfer description displays transfer_desc=Logical Transfer with Storage Efficiency, SnapMirror is maintaining storage efficiency. If the transfer description displays transfer_desc=Logical Transfer, SnapMirror is not maintaining storage efficiency. For example:

Fri May 22 02:13:02 CDT 2020 ScheduledUpdate[May 22 02:12:00]:cc0fbc29-b665-11e5-a626-00a09860c273 Operation-Uuid=39fbcf48-550a-4282-a906-df35632c73a1 Group=none Operation-Cookie=0 action=End source=<sourcepath> destination=<destpath> status=Success bytes_transferred=117080571 network_compression_ratio=1.0:1 transfer_desc=Logical Transfer - Optimized Directory Mode

Before you begin

The source and destination clusters and SVMs must be peered.
You must disable postprocess compression on the destination volume.
Logical Transfer with storage: Manual update is no longer required to re-enable storage efficiency. If SnapMirror detects that postprocess compression has been disabled, it automatically re-enables storage efficiency at the next scheduled update.
ETERNUS AX/AC series manage storage efficiency settings differently from ETERNUS HX series after a destination volume is made writeable:
- After you make a destination volume writeable using the snapmirror break command, the caching policy on the volume is automatically set to auto (the default).
  
  This behavior is applicable to FlexVol volumes, only, and it does not apply to FlexGroup volumes.
  
  Learn more about snapmirror break in the ONTAP command reference.
- On resync, the caching policy is automatically set to none, and deduplication and inline compression are automatically disabled, regardless of your original settings. You must modify the settings manually as needed.

Manual updates with storage efficiency enabled can be time-consuming. You might want to run the operation in off-peak hours.

Steps

Update a replication relationship and re-enable storage efficiency:

snapmirror update -source-path <SVM:volume>|<cluster://SVM/volume>, ... -destination-path <SVM:volume>|<cluster://SVM/volume>, ... -enable-storage-efficiency true

You must run this command from the destination SVM or the destination cluster. The command fails if a common snapshot does not exist on the source and destination. Use snapmirror initialize to re-initialize the relationship. Learn more about snapmirror initialize in the ONTAP command reference.

The following example updates the relationship between the source volume volA on svm1 and the destination volume volA_dst on svm_backup, and re-enables storage efficiency:

cluster_dst::> snapmirror update -source-path svm1:volA -destination-path svm_backup:volA_dst -enable-storage-efficiency true

Learn more about snapmirror update in the ONTAP command reference.

ONTAP 9 Manuals ( CA08871-402 )

Manage storage efficiency on ONTAP SnapMirror volumes

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