What is the purpose of SnapMirror logs in clustered Data ONTAP?

Background information

SnapMirror 'Relationship Capability' in clustered Data ONTAP 8.2 and later:

• 'Pre clustered Data ONTAP 8.2': Management and control of the relationship is compatible with clustered Data ONTAP 8.1, known as clustered Data ONTAP 8.1 style SnapMirror.
• 'Clustered Data ONTAP 8.2 and later': Full support of Data ONTAP 8.2 or later, clustered Data ONTAP SnapMirror relationship management and control, known as clustered Data ONTAP 8.2 style SnapMirror
  In other words, 'Pre clustered Data ONTAP 8.2' style SnapMirror relationship could still exist on clustered Data ONTAP 8.2. Check this setting by running the 'snapmirror show –instance' command, and check the 'Relationship Capacity' field.

Clustered Data ONTAP 8.1 style SnapMirror

• /mroot/etc/log/mlog/snapmirror.log*            : SnapMirror activity is primarily logged here
• /mroot/etc/log/mlog/command-history.log* : All the commands run to manage SnapMirror is available here
• /mroot/etc/log/mlog/mgwd.log*            : SnapMirror service job logs is available here, especially for LS Mirrors related logs
• /mroot/etc/log/ems.log*                  : The ones for clustered Data ONTAP 8.1 style begin with 'mgmt_snapmir'

Clustered Data ONTAP 8.2 style SnapMirror

• /mroot/etc/log/snapmirror_audit*  : Audit logs for SnapMirror operations
• /mroot/etc/log/snapmirror_error*  : Error is logged here
• /mroot/etc/log/mlog/mgwd.log*     : The same information as with clustered Data ONTAP 8.1 style SnapMirror
• /mroot/etc/log/ems.log*           : The ones for clustered Data ONTAP 8.1 style begin with 'smc_snapmir'

Does AutoSupport (ASUP) contain these contents?

snapmirror_error*, ems.log*, command-history.log*, and mgwd.log* are included in the daily or manually triggered (type all) AutoSupport. Weekly ASUP does not contain this information.

What is the SnapMirror log naming convention?

The following is an example for /mroot/etc/log/mlog/snapmirror.log*:
cm2552a-cn-01% pwd
/mroot/etc/log/mlog
cm2552a-cn-01% ls -al snapmirror*
-rw-r--r-- 2 root wheel 0 Sep 22 15:49 snapmirror.log
-rw-r--r-- 1 root wheel 1004 Sep 7 19:24 snapmirror.log.0000000001
-rw-r--r-- 1 root wheel 0 Sep 8 15:48 snapmirror.log.0000000002
-rw-r--r-- 1 root wheel 0 Sep 9 15:48 snapmirror.log.0000000003
-rw-r--r-- 1 root wheel 0 Sep 10 15:48 snapmirror.log.0000000004
-rw-r--r-- 1 root wheel 0 Sep 11 15:48 snapmirror.log.0000000005
-rw-r--r-- 1 root wheel 0 Sep 12 15:48 snapmirror.log.0000000006
-rw-r--r-- 1 root wheel 0 Sep 13 15:48 snapmirror.log.0000000007
-rw-r--r-- 1 root wheel 0 Sep 14 15:48 snapmirror.log.0000000008
-rw-r--r-- 1 root wheel 0 Sep 15 15:48 snapmirror.log.0000000009
-rw-r--r-- 1 root wheel 0 Sep 16 15:48 snapmirror.log.0000000010
-rw-r--r-- 1 root wheel 0 Sep 17 15:48 snapmirror.log.0000000011
-rw-r--r-- 1 root wheel 0 Sep 18 15:49 snapmirror.log.0000000012
-rw-r--r-- 1 root wheel 0 Sep 19 15:49 snapmirror.log.0000000013
-rw-r--r-- 1 root wheel 0 Sep 20 15:49 snapmirror.log.0000000014
-rw-r--r-- 1 root wheel 0 Sep 21 15:49 snapmirror.log.0000000015
-rw-r--r-- 2 root wheel 0 Sep 22 15:49 snapmirror.log.0000000016

Snapmirror.log.0000000001 is the oldest log, while the one with the largest number is the latest log that has the same contents of snapmirror.log.
Note: The same rule applies to mgwd.log* and command-history.log* (both are in /mroot/etc/log/mlog), and the ems.log* in /mroot/etc/log.

The following is an example for /mroot/etc/log/snapmirror_audit*:

cm2552a-cn-01% pwd /mroot/etc/log

cm2552a-cn-01% ls -al snapmirror_audit*
-rw-r--r-- 2 root wheel 542 Sep 22 15:49 snapmirror_audit
-rw-r--r-- 2 root wheel 3070 Sep 20 15:48 snapmirror_audit.0
-rw-r--r-- 2 root wheel 6725 Sep 13 15:46 snapmirror_audit.1
-rw-r--r-- 2 root wheel 70 Jul 11 23:47 snapmirror_audit.10
-rw-r--r-- 2 root wheel 2228 Sep 6 15:45 snapmirror_audit.2
-rw-r--r-- 2 root wheel 1897 Aug 30 21:48 snapmirror_audit.3
-rw-r--r-- 2 root wheel 3572 Aug 23 21:47 snapmirror_audit.4
-rw-r--r-- 2 root wheel 2099 Aug 16 22:02 snapmirror_audit.5
-rw-r--r-- 2 root wheel 1897 Aug 9 22:54 snapmirror_audit.6
-rw-r--r-- 2 root wheel 1897 Aug 2 22:52 snapmirror_audit.7
-rw-r--r-- 2 root wheel 1897 Jul 26 22:51 snapmirror_audit.8
-rw-r--r-- 2 root wheel 1696 Jul 19 22:49 snapmirror_audit.9
-rw-r--r-- 2 root wheel 70 Jul 11 23:47 snapmirror_audit.log.0000000001
-rw-r--r-- 2 root wheel 1696 Jul 19 22:49 snapmirror_audit.log.0000000002
-rw-r--r-- 2 root wheel 1897 Jul 26 22:51 snapmirror_audit.log.0000000003
-rw-r--r-- 2 root wheel 1897 Aug 2 22:52 snapmirror_audit.log.0000000004
-rw-r--r-- 2 root wheel 1897 Aug 9 22:54 snapmirror_audit.log.0000000005
-rw-r--r-- 2 root wheel 2099 Aug 16 22:02 snapmirror_audit.log.0000000006
-rw-r--r-- 2 root wheel 3572 Aug 23 21:47 snapmirror_audit.log.0000000007
-rw-r--r-- 2 root wheel 1897 Aug 30 21:48 snapmirror_audit.log.0000000008
-rw-r--r-- 2 root wheel 2228 Sep 6 15:45 snapmirror_audit.log.0000000009
-rw-r--r-- 2 root wheel 6725 Sep 13 15:46 snapmirror_audit.log.0000000010
-rw-r--r-- 2 root wheel 3070 Sep 20 15:48 snapmirror_audit.log.0000000011
-rw-r--r-- 2 root wheel 542 Sep 22 15:49 snapmirror_audit.log.0000000012

Mgwd is currently maintaining two sets of snapmirror_audit* and snapmirror_error* logs, which have identical information and time stamps. In this case,
snapmirror_audit.10 = snapmirror_audit.log.0000000001 are the oldest logs and snapmirror_audit = snapmirror_audit.log.0000000012 are the latest logs.

These two sets of logs are different in the way they rotate and their retaining periods. As they have the identical information logged, only one set of logs needs to be checked. snapmirror_audit.log.xxxxxxxxxx and snapmirror_audit.log.xxxxxxxxxx are recommended as their retaining period is longer, and the way they rotate makes it easier to read.