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Old 6th July 2011
Randux Randux is offline
Disgruntled desktop user
Join Date: May 2008
Location: Siberia
Posts: 100

Originally Posted by Carpetsmoker View Post
OpenSolaris and Solaris use ZFS almost exclusively. Even on a single-disk single-filesystem layout.
Ok I have to agree with Oko on this one.

Yes, it's true ZFS is used a lot on Solaris (I don't know about OpenSolaris since I don't use it) but the default Solaris 10 install is still UFS. 99.9% of Solaris 10 installs are on big systems with many drives. If you follow the opensolaris zfs list (I do) you can see the questions they ask, nobody ever asked about one drive. They are talking about issues with dozens of drives, setups I would love to have!

ZFS on a single drive isn't totally useless, because you do get very nice features like snapshots and not having to decide the size of your partitions when you install. But the main feature that makes ZFS popular for enterprise use is the checksumming and recovery. If you have a single drive all the system can tell you is your filesystem or drive is no good, and refuse to use it. That might even be worse in some cases then UFS. If you have at least two drives, you have a very good chance of surviving the total loss of one drive or heavy corruption on one drive.

I recently had a BIOS problem on a Solaris 10 machine with a dead CMOS battery with 2 drives in mirror config. The system came up and started frying one of my drives. I got diagnostic messages from ZFS (although it went into a shutdown and reboot loop) and was able to start in single user mode and find the bad files and do a scrub on the pool and I lost nothing. I would have lost about a month's worth of work if I didn't use ZFS. So yeah, ZFS is great but you really need *at least* two drives or you won't get the most advantage. Drives are cheap. You should really have two if you use ZFS. I have no experience on BSD with ZFS though.

And BTW to sharris, ZFS people tell you "DO NOT USE HARDWARE RAID!" if you use ZFS. Let ZFS manage the configuration. You have many ZFS RAID options.
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