According to the metadb man page:
Now based on italicized part, if a mirror only has a single replica and never crashes, it should still function.
Same with booting. I thought three replicas were necessary for the system to be able to come up but the comment about crashing tells me that as long as the mirrors are stable (iow never crash), the system should come up.
The reason I ask this is that I've started a new position and discovered 8 disks in need of maintenance (metareplace), one disk out of sync (all partitions) and one disk with the status of Unknown.
In addition, I found several replicas that have failed (W - write errors and M - replica had problem with master blocks) and quite a few with less than 3 replicas on a disk (I prefer to configure a system with a mininum of 3 replicas per disk since disks are so large). At least one system had only a single replica database and 2 or 3 had two replica databases.
Per the comment in the man page, you need a majority (technically one is a majority) for the state information to be validated.
The problem is that systems are functioning correctly with one or two replicas and the one with a single replica was rebooted four days ago. Since it was booted, I have to believe that three replicas aren't required. In fact, as long as the replica db is stable, you can boot with a single replica (based on evidence).
So:
How does a system with only two replicas still manage to operate correctly? I can logically see how one will work (majority) but only two should fail.
Are my thoughts on a single replica and the system not crashing accurate? Or at least logical
My next steps appear to be to get the bad disks replaced (easy enough) but also to get the replicas in order. For the systems with 1 or 2 replicas, I think I'm going to have to break the mirrors and rebuild with what I think is the correct number of replicas (some of the disks have 5 replicas per disk).
Thoughts? Pointers to more technical information that what's on docs.sun.com?
Thanks.
Carl