Justin> Another pretty major difference between LS and DP methods; Justin> DP method requires manual intervention when a failover/restore is needed.
This is fine in my case, because I'm really trying to protect against a shipping failure, though it's tempting to do more to protect against root volume failures as well. Though I've honestly never had one, nor had a netapp fail so badly in 22+ years of using them that I lost data from hardware failures.
Closest I came was on a F740 (I think) using the DEC StorageWorks canisters and shelves. I had a two disk failure in an aggregate. One disk you could hear scrapping the heads on the platter, the other was a controller board failure. Since I had nothing to lose, I took the good controller board off the head crash drive and put it onto the other disk. System came up and found the data and started rebuilding. Whew! Raid-DP is a good thing today for sure.
Justin> LS Mirrors are running in parallel and incoming reads/access Justin> requests (other than NFSv4) hit the LS mirrors rather than the Justin> source volume, so if one fails, you don’t have to do anything Justin> right away; you’d just need to resolve the issue at some Justin> point, but no interruption to service.
That's a decent reason to use them.
Justin> LS mirrors can also have a schedule to run to avoid needing to Justin> update them regularly. And, if you need to write to the SVM Justin> root for some reason, you’d need to access the .admin path in Justin> the vsroot; LS mirrors are readonly (like DP mirrors).
The default for 9.3 seems to be 1 hour, but I bumped it to every 5 minutes, because I have Netbackup backups which use snapshots and 'vol clone ...' to mount Oracle volumes for backups. I had to hack my backuppolicy.sh script to put in a 'sleep 305' to make it work properly.
Trying to make it work generically with 'snapmirror update-ls-set <vserver>:<source>' wasn't working for some reason, so the quick hack of a sleep got me working.
But I am thinking of dropping the LS mirrors and just going with DP mirrors of all my rootvols instead, just because of this issue.
But let's do a survey, how many people on here are using LS mirrors of your rootvols on your clusters? I certainly wasn't across multiple clusters.
Jhn