2018-04-05 01:31 AM
For too many years we've been using DP snapmirror relationships to maintain identical copies of volumes between the source and destination. Given we have a policy for multiple weeks of online backups this makes for some overhead on the source side.
I have been looking into switching to XDP policies so as to reduce the soure snapshot retention whilst maintaining the higher number on the destination side. I believe this would have the added benefit of version independence but isn't the greatest for DR on the basis it's not straightforward to make such a destination volume read/writable.
I came across MirrorAndVault yesterday which on the face of it appears to be the best of both worlds. Mirrored snapshot of the active filesystem plus the flexibility of higher numbers of snapshots on the destination for online backups.
What I'd like help clarifying is:
Are there any other pros/cons to weigh up?
Currently we are running 9.1p8
Thanks for your time.
2018-04-05 08:12 AM
To keep it short:
-> yes the breaking process is the same as a standard DP or XDP relationship. When you issue a snapmirror break command or break it in System Manager, the destination volumes become writable.
-> For SnapMirror interoperability, check the Data Protection Power Guide for your ONTAP release (page 72-73), output attached.
Regarding considerations, it really depends on your systems and the amount of relationships that you have.
Performance should be measured accordingly to avoid having lag issues.
Hope that helps.
2018-04-05 08:50 AM
Thanks for taking the time to respond Ron
On the face of it that appears to suggest that for a snapmirror relationship of type XDP and policy-type mirror-vault we could, for instance, move the source to 9.3 and leave the destination on 9.1 which is good news.
One other item I've found in some of the docs is reference to the "sm_created" snapmirror-label, for instance in the rules section of the MirrorAndVault policy:
SnapMirror Label Keep Preserve Warn Schedule Prefix
----------------------------- ---- -------- ---- -------- ----------
sm_created 1 false 0 - -
daily 7 false 0 - -
weekly 52 false 0 - -
Whilst I understand how to create the snapmirror labels for daily and weekly in the source snapshot policies, I don't see how the sm_created label is supposed to get created for the snapmirror snapshot itself:
::> snapshot show limk_div_mavtest -fields snapmirror-label
vserver volume snapshot snapmirror-label
---------- ---------------- --------- ----------------
limkdrntap limk_div_mavtest bobstest3 daily
limkdrntap limk_div_mavtest bobstest4 daily
limkdrntap limk_div_mavtest bobstest5 daily
limkdrntap limk_div_mavtest bobstest6 daily
limkdrntap limk_div_mavtest bobstest7 daily
limkdrntap limk_div_mavtest bobstest8 daily
limkdrntap limk_div_mavtest bobstest9 daily
limkdrntap limk_div_mavtest snapmirror.64d67436-dc46-11e3-aa00-123478563412_2148469589.2018-04-05_155840
limkdrntap limk_div_mavtest snapmirror.64d67436-dc46-11e3-aa00-123478563412_2148469589.2018-04-05_160039
I assumed it should be added by default for any snapmirror but it clearly doesn't for me.