Matt, > Just to clarify a few items... consider a setup where we desire to > use AVS to replicate the ZFS pool on a 4 drive server to like > hardware. The 4 drives are setup as RaidZ. > > If we lose a drive (say #2) in the primary server, RaidZ will take > over, and our data will still be "available" but the array is at a > degraded state. > > But what happens to the secondary server? Specifically to its bit- > for-bit copy of Drive #2... presumably it is still good, but ZFS > will offline that disk on the primary server, replicate the > metadata, and when/if I "promote" the seconday server, it will also > be running in a degraded state (ie: 3 out of 4 drives). correct?
The issue with any form of RAID >1, is that the instant a disk fails out of the RAID set, with the next write I/O to the remaining members of the RAID set, the failed disk (and its replica) are instantly out of sync. > In this scenario, my replication hasn't really bought me any > increased availablity... or am I missing something? In testing with ZFS in the scenario, first of all the secondary node's ZPOOL is not in the import state. So if one stops replication, or there is a primary node failure, a zpool import operation will need to be done on the secondary node. In all my testing to date, ZFS does the correct thing, realizing that one disk had failed out of the RAID set on the primary, and thus to not use it on the secondary. In short, ZFS knows that the RAID set is degraded, was being maintained in a degraded state, and this fact was replicated to the secondary node, correctly. > Also, if I do chose to fail over to the secondary, can I just to a > scrub the "broken" drive (which isn't really broken, but the zpool > would be inconsistent at some level with the other "online" drives) > and get back to "full speed" quickly? or will I always have to wait > until one of the servers resilvers itself (from scratch?), and re- > replicates itself?? > > thanks in advance. > > -Matt > -- > This message posted from opensolaris.org > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss Jim Dunham Engineering Manager Storage Platform Software Group Sun Microsystems, Inc. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
