Planning for upgrading filers running SnapMirror

Upgrade requirements for SnapMirror

If you are upgrading Data ONTAP on filers that are running SnapMirror, you must upgrade the filers that have SnapMirror destination volumes before you upgrade the filers that have SnapMirror source volumes. For SnapMirror volume replication, the destination volume must run under a version of Data ONTAP equal to or later than that of the SnapMirror source volume.

This requirement applies to both asynchronous and synchronous SnapMirror deployments.

Caution
If you do not upgrade the filers that have SnapMirror destination volumes before upgrading those that have source volumes (in other words, if you do not upgrade SnapMirror destination and source filers in the correct order), SnapMirror volume replication will be disabled.

Identifying SnapMirror destination volumes

SnapMirror source volumes can be replicated to single or multiple destination volumes (replication to multiple destination volumes is also referred to as replication to cascading destinations). When you upgrade Data ONTAP, you must identify all destination volumes and then upgrade the filers on which they reside before upgrading the filer where the source volume resides. In addition, when you upgrade filers in a cascading series, upgrade the filers in order, beginning with the destination filers furthest in your topology from the source filer.

To identify filers with SnapMirror destination volumes, complete the following step.

Step	Action
1	On the filer with the source volume, enter the following command: snapmirror destinations Result The `snapmirror` command lists all destination volumes, including cascaded destinations. For more information about the `snapmirror` command and options, see the NetApp snapmirror(1) man page.

Upgrading filers running synchronous SnapMirror

When you upgrade Data ONTAP on filers running synchronous SnapMirror, SnapMirror goes into an asynchronous mode. When in asynchronous mode, the source filer asynchronously replicates data to the destination every minute until a synchronous replication can be reestablished.

Why you must plan for SnapMirror upgrades

When you upgrade Data ONTAP on filers that have a mirrored relationship with each other using SnapMirror, the order in which you upgrade the filers is critical. If you do not upgrade in the correct order, you can cause a lapse in SnapMirror replication coverage.

A SnapMirror transfer is initiated when the destination filer reads a snapshot of the source filer. Therefore, the destination filer must be upgraded first, so that it can read the snapshots of the earlier release. If the source filer is upgraded first, the destination filer cannot read the source filer's file system, thereby disabling SnapMirror.

For more information

For more information about running SnapMirror on filers configured for network attached storage (NAS), see the Data Protection Online Backup and Recovery Guide.

For a description of SnapMirror implementation and management on filers configured for a storage area network (SAN) environment, see the SAN Setup Overview FCP 1.1 Guide.