You have a large 2PiB flexgroup that will need to be failed over to a DR site for a weekend due to maintenance work at the original site. To speed up…

The snapmirror resync command, including the -quick-resync option, synchronizes the destination volume with the source. In this scenario of reversing the relationship, the original source volume becomes the destination of the resync operation. This process overwrites the data on the original source volume with the changes made at the DR site. As a result, the existing block layout and metadata that provided storage efficiency savings (such as deduplication, compression, and compaction) on that original source volume are invalidated and lost. Storage efficiency scanners must be run again post-resync to reclaim space.

A. All storage efficiencies will be preserved: This is incorrect. The resync operation is an overwrite process on the destination (original source), which inherently breaks existing storage efficiencies.

B. All storage efficiencies are done in line with the SnapMirror: This is incorrect. While SnapMirror can preserve efficiencies on transfer, the resync operation's primary function is data synchronization, not applying efficiencies in-line.

C. All storage efficiencies will be ignored: This is imprecise. The process doesn't simply "ignore" efficiencies; it actively removes them by overwriting the data blocks on the destination volume.

1. NetApp ONTAP 9 Data Protection Power Guide

Reference: In the section "Reactivating the original source volume," the guide describes the snapmirror resync command. It states, "The resync operation makes the destination volume a read-only copy of the source volume." This overwrite mechanism is what causes the loss of pre-existing storage efficiencies on the destination volume (which, in this scenario, is the original source).

Document: NetApp ONTAP 9 Data Protection Power Guide (e.g., for ONTAP 9.8), Page 41.

2. NetApp Technical Report TR-4015: SnapMirror Configuration and Best Practices Guide for ONTAP 9

Reference: Section 5.3, "Resynchronizing a relationship after a failover," details the resync process. The report explains that resync overwrites the destination volume to match the source. This action discards the unique data layout on the destination, thereby eliminating any storage savings from deduplication or compression that existed prior to the operation.

Document: TR-4015, Section 5.3.

3. NetApp ONTAP Command Reference: snapmirror resync

Reference: The official command documentation for snapmirror resync states its function is to "resynchronize the contents of the destination with the contents of the source." This confirms that the destination is made to be a copy of the source, a process that does not preserve the destination's original storage efficiency characteristics.

Document: snapmirror resync man page, available through the ONTAP CLI or the NetApp Documentation Center.