Date: Thu, 18 Dec 2008 21:37:39 -0800 From: Matt Simerson <matt@corp.spry.com> To: freebsd-fs@freebsd.org Subject: Re: ZFS performance gains real or imaginary? Message-ID: <D18EBA53-704F-4C21-9BF9-CDBB2AF918D2@corp.spry.com> In-Reply-To: <alpine.BSF.2.00.0812181732440.14585@ibyngvyr.purzvxnyf.bet> References: <22C8092E-210F-4E91-AA09-CFD38966975C@spry.com> <alpine.BSF.2.00.0812181732440.14585@ibyngvyr.purzvxnyf.bet>
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On Dec 18, 2008, at 4:48 PM, Wes Morgan wrote: >> On the two systems above (amd64 with 16GB of RAM and 24 1TB disks) >> I get about 30 days of uptime before the system hangs with a ZFS >> error. They write backups to disk 24x7 and never stop. I could not >> anything near that level of stability with back03 (below) which was >> much older hardware maxed out at 4GB of RAM. I finally resolved >> the stability issues on back03 by ditching ZFS and using >> geom_stripe across the two hardware RAID arrays. > > Were you doing a zfs mirror across two hardware raid arrays? The > performance of that type of setup would probably be sub-optimal > versus a zpool with two raidz volumes. I haven't benchmarked it with -HEAD but with FreeBSD 7, using a ZFS mirror across two 12-disk hardware RAID arrays (Areca 1231ML) was significantly (not quite double) faster than using JBOD and raidz. I tested a few variations (four disk pools, six disk zpools, 8 disk zpools, etc). I'll be getting another 24 disk system to add to my backup pool in a month or two. When it arrives, I'll run some additional benchmarks with -HEAD and see where the numbers fall. I'll be quite surprised if raidz can outrun a hardware RAID controller with 512MB of BBWC. Matt
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