From: Clifton Royston (no email)
Date: Mon Apr 01 2002 - 13:43:05 EST
On Mon, Apr 01, 2002 at 10:50:30AM +0100, Dominic Marks wrote:
> On Sun, Mar 31, 2002 at 08:23:19PM -0800, Keith Woodworth wrote:
> > On Sun, 31 Mar 2002, Ralf Hildebrandt wrote:
> > |->On Sat, Mar 30, 2002 at 02:31:00PM -0800, Keith Woodworth wrote:
> > |->> since switching to postfix I seem to see a little delay in processing
> > |->> command line stuff. For ex. I'll do an ls it takes about 5 secs soemtimes
> > |->> and other times it take a split second in the same dir.
> > |->
> > |->Do you use ext3?
> >
> > No its under BSD/OS. CPU usage is mostly 90%+ idle. But I'm thinking the
> > IDE disk is where is causing these little hesitations.
>
> I don't know if softupdates, as used in the *BSDs ever made it into
> BSD/OS. If they did - make sure they are turned on. It makes a big
> difference on slower discs.
As it happens, I've just been doing a lot of testing of BSD/OS under
heavy disk load (though on SCSI-based systems.) You might want to check
recent archives for bsdi-users for some of my comments there.
Softupdates appears to be safe on *some* systems from BSD/OS 4.1 on,
but not on others, and it's not clear what the exact parameters are. On
the one hand, I crashed my test server with BSD/OS 4.1 and corrupted
the file system (SCSI RAID) in less than 10 minutes of heavy load
testing with softupdates turned on. On the other hand, another poster
to that list has a heavily-used news server running with 4.1 and
softupdates, with over a year of uptime. At the moment I suspect the
"aic" SCSI drivers may be part of the problem, but it's unclear.
The message: Test softupdates on a scratch server running your same
application mix before you turn it on on your main server. If you
don't have a scratch server, tread cautiously.
> Another FreeBSD technology is DirHash
> which may not be directly useful here but is brilliant in some
> circumstances - and removes more acitivity from the disc. Again,
> perhaps BSD/OS has implementated these or similar things.
Unfortunately not. Netapp's Postmark benchmark measures horrendous
degradation in performance on BSD/OS when you go from 1K files to 10K
files in a directory.
Despite the best will and expertise of their developers, BSD/OS has
been slowly lagging more and more behind FreeBSD in terms of stability,
new features, and performance. (SCSI tagged command queueing also
seems to work better in FreeBSD, and the throughput I measure in
benchmarks like iozone is anywhere from 10%-50% higher on many
measurements under FreeBSD.) Most BSDI customers seem to expect things
to get worse under WindRiver's ownership based on the kind of support
we've seen so far. I've been thinking the next couple quarters may be
the time to start moving more of our servers to FreeBSD, probably
starting with our mail relay servers.
-- Clifton
--
Clifton Royston -- LavaNet Systems Architect --
"What do we need to make our world come alive?
What does it take to make us sing?
While we're waiting for the next one to arrive..." - Sisters of Mercy
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