mps(4) driver (LSI 6Gb SAS) commited to stable/8

Dmitry Morozovsky marck at
Sat Feb 19 08:37:22 UTC 2011

On Fri, 18 Feb 2011, Jeremy Chadwick wrote:

JC> > KDM> The best stress test I have found has been to just do a single sequential
JC> > KDM> write stream with ZFS.  i.e.:
JC> > KDM> 
JC> > KDM> cd /path/to/zfs/pool
JC> > KDM> dd if=/dev/zero of=foo bs=1M
JC> > KDM> 
JC> > KDM> Just let it run for a long period of time and see what happens.
JC> > 
JC> > Well, provided that I'm plannign to use ZFSv28 to be in place, wouldn't be 
JC> > /dev/random more appropriate?
JC> No -- /dev/urandom maybe, but not /dev/random.  /dev/urandom will also
JC> induce significantly higher CPU load than /dev/zero will.  Don't forget
JC> that ZFS is a processor-centric (read: no offloading) system.

We're not on Linux:

root at beaver:/FreeBSD/src.8# l /dev/*random
crw-rw-rw-  1 root  wheel    0,  23 Feb 15 13:50 /dev/random
lrwxr-xr-x  1 root  wheel         6 Feb 15 13:50 /dev/urandom@ -> random

JC> I tend to try different block sizes (starting at bs=8k and working up to
JC> bs=256k) for sequential benchmarks.  The "sweet spot" on most disks I've
JC> found is 64k.  Otherwise use benchmarks/bonnie++.

Ah yes, bonnie++ was on my list too, thanks for the reminder.

D.Marck                                     [DM5020, MCK-RIPE, DM3-RIPN]
[ FreeBSD committer:                                 marck at ]
*** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck at ***

More information about the freebsd-stable mailing list