LS_Mirrors & SVM_DR Best Practices

[brasseurm]

Hello all,

I have some questions regarding the usage of LS_Mirrors in a SVM_DR configuration.  I've read it is a Best Practice to use LS_Mirrors to protect root volumes in a NAS environment.  My system is a 4 nodes cluster, using only FlexVol and with CIFS SVM_DR.

• Is it "mandatory" or really "recommanded" to put one a on each 4 nodes of the cluster, since the aggregates where the volumes reside are owned by a single HA Pair ?
• What's your recommandation regarding snapshots of these LS_Mirror volumes ?
• What about performance, is it really worth to use it ?
• Do you have any example of circumstance when you can lose a root volume and, thus promote a LS_Mirror ?

Thank you for your help, do not hesitate to provide me any other guideline about this...

[GidonMarcus]

• Is it "mandatory" or really "recommanded" to put one a on each 4 nodes of the cluster, since the aggregates where the volumes reside are owned by a single HA Pair ?
  • highly recommend
• What's your recommendation regarding snapshots of these LS_Mirror volumes ?
  • no need to. you can't restore them or the root volume itself. you can only create new ones.
• What about performance, is it really worth to use it ?
  • it should not have good or bad impact on performance
• Do you have any example of circumstance when you can lose a root volume and, thus promote a LS_Mirror ?
  • it will allow you to continue and serve data from other nodes in case of a failure affecting the hosting aggregate (corruption. raid degradation for example in a case of multi-disk failure, the node freeze (watchdog likely to take a few sec/min to detect, etc... etc...)

Gidi

[brasseurm]

Thanks Gidi for you reply, very useful.

I guess it is not needed neither to snapshot the root volumes?  There's no particular situation where you have to restore it...?

As I know, there are "entry point" for the namespace only and should not contain any user data, but is there any configuration data on it ?

I aslo read SVM DR didn't replicate root volumes, but somewhere else I read a contradiction...  which affirmation is correct ?

Regarding performance, the LS_Mirrors are entry points for the namespace, is this means IO would go through it, is it worth to place root volumes and LS_mirrors on an faster aggregate ?

Thank you guys !