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How does the "schedule" parameter in an ONTAP 9 SnapMirror policy rule work?

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Applies to

  • ONTAP 9

Answer

In ONTAP 9, SnapMirror relationships of all types are still scheduled via the schedule parameter on the SnapMirror relationship itself, as seen in snapmirror show -instance.
ClusterDR::> snapmirror show -instance

            Source Path: svmSrc:volSrc
       Destination Path: svmDst:volDst
      Relationship Type: XDP
Relationship Group Type: none
    SnapMirror Schedule: daily

...

In ONTAP 9, SnapMirror policies have a new and separate schedule parameter that can be configured as part of a SnapMirror policy rule. This parameter can be seen in snapmirror policy show -instance and is an option when creating or modifying a SnapMirror policy rule with snapmirror policy add-rule and snapmirror policy modify-rule. This article discusses the use of this schedule.
ClusterDR::> snapmirror policy show -policy CustomMirrorVault -instance

                    Vserver: ClusterDR
     SnapMirror Policy Name: CustomMirrorVault
     SnapMirror Policy Type: vault
               Policy Owner: cluster-admin
                Tries Limit: 8
          Transfer Priority: normal
  Ignore accesstime Enabled: false
    Transfer Restartability: always
Network Compression Enabled: false
            Create Snapshot: false
                    Comment: -
      Total Number of Rules: 2
                 Total Keep: 15
                      Rules:
SnapMirror Label              Keep Preserve Warn Schedule Prefix
----------------------------- ---- -------- ---- -------- ----------
 daily                          10 false       0 -        -
 weekly                          5 false       0 weekly   weekly

ClusterDR::> snapmirror policy add-rule ?
    -vserver                   Vserver Name
   [-policy]                   SnapMirror Policy Name
   [-snapmirror-label]         Snapshot Copy Label
   [-keep]                     Snapshot Copy Retention Count
  [[-preserve] {true|false}]   Snapshot Copy Preserve Enabled
  [ -warn <integer> ]          Warning Threshold Count
  [ -schedule ]                Snapshot Copy Creation Schedule
  [ -prefix ]                  Snapshot Copy Creation Prefix


This schedule parameter found in a SnapMirror policy rule is not a transfer schedule and will not trigger a backup. Instead, this schedule controls a new feature known as secondary SnapVault Snapshot copies. This feature creates independent snapshot copies on a SnapVault secondary volume without having to create and maintain a corresponding Snapshot copy on the SnapVault Primary. When a schedule is used in a SnapMirror policy rule assigned to a SnapMirror relationship, that rule will create snapshots on the SnapVault secondary volume when the schedule triggers. These rules will not trigger an update and snapshots with the configured label will not be backed up from the primary volume. If you want your rule to back up snapshots from the SnapVault primary volume, re-create your rule without the schedule parameter. Other high-level details and caveats for the Secondary SnapVault Snapshot copy feature:

  • This feature is only available for use with vault and mirror-vault type SnapMirror policies.
  • You must have at least one rule in your SnapMirror policy with no schedule parameter.
  • This feature is only available in ONTAP 9 and later.
  • The Destination System needs to be running, otherwise no Snapshot is taken at the scheduled time

Additional Information