On 09 October, 2009 - Brandon Hume sent me these 2,0K bytes: > I've got a mail machine here that I built using ZFS boot/root. It's > been having some major I/O performance problems, which I posted once > before... but that post seems to have disappeared. > > Now I've managed to obtain another identical machine, and I've built > it in the same way as the original. Running Solaris 10 U6, I've got > it fully patched as of 2009/10/06. It's using a mirrored disk via the > PERC (LSI Megaraid) controller. > > The main problem seems to be ZFS. If I do the following on a UFS filesystem: > > # /usr/bin/time dd if=/dev/zero of=whee.bin bs=1024000 count=<x> > > ... then I get "real" times of the following: > > x time > 128 35. 4 > 256 1:01.8 > 512 2:19.8
Is this minutes:seconds.millisecs ? if so, you're looking at 3-4MB/s .. I would say something is wrong. > It's all very linear and fairly decent. Decent?! > However, if I then destroy that filesystem and recreate it using ZFS > (no special options or kernel variables set) performance degrades > substantially. With the same dd, I get: > > x time > 128 3:45.3 > 256 6:52.7 > 512 15:40.4 0.5MB/s .. that's floppy speed :P > So basically a 6.5x loss across the board. I realize that a simple > 'dd' is an extremely weak test, but real-world use on these machines > shows similar problems... long delays logging in, and running a > command that isn't cached can take 20-30 seconds (even something as > simple as 'psrinfo -vp'). > > Ironically, the machine works just fine for simple email, because the > files are small and very transient and thus can exist quite easily > just in memory. But more complex things, like a local copy of our > mailmaps, cripples the machine. .. because something is messed up, and for some reason ZFS seems to feel worse than UFS.. > I'm about to rebuild the machine with the RAID controller in > passthrough mode, and I'll see what that accomplishes. Most of the > machines here are Linux and use the hardware RAID1, so I was/am > hesitant to "break standard" that way. Does anyone have any > experience or suggestions for trying to make ZFS boot+root work fine > on this machine? Check for instance 'iostat -xnzmp 1' while doing this and see if any disk is behaving badly, high service times etc.. Even your speedy 3-4MB/s is nowhere close to what you should be getting, unless you've connected a bunch of floppy drives to your PERC.. /Tomas -- Tomas Ögren, st...@acc.umu.se, http://www.acc.umu.se/~stric/ |- Student at Computing Science, University of Umeå `- Sysadmin at {cs,acc}.umu.se _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
