Date: Wed, 13 May 2009 16:05:03 +0200 From: Tijl Coosemans <tijl@ulyssis.org> To: freebsd-questions@freebsd.org, Andy Dills <andy@xecu.net> Subject: Re: Extreme filesystem performance decrese going from FreeBSD4 to FreeBSD7 Message-ID: <200905131605.04534.tijl@ulyssis.org> In-Reply-To: <20090512135226.N64283@shell.xecu.net> References: <20090512135226.N64283@shell.xecu.net>
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On Tuesday 12 May 2009 20:16:21 Andy Dills wrote: > A customer of a customer needed to expand the size of the filesystem > on a webserver they run, and since it was still running 4.11, they > decided to go ahead and upgrade to 7.1. > > Unfortunately, they have seen the performance decrease significantly. > Now, under 7.1, numerous perl processes will queue up (from their web > applications), the load average will be in the 40s to 90s, and > according to top they perl scripts are commonly in the "ufs" state, > which I assume means stuck waiting for read or write responses. > > I have also experienced pretty abysmal read performance from the > array, using dd...we're talking sub 1MBps. So, my assumption is that > something is wrong on the filesystem layer. > > When I look at the CPU utilization in top, I see that 80-90% is > constantly used by "system". > > However, when I look at iostat, I see very low numbers for the raid, > in fact across the board. > > It's a Dell server with a Perc4/Di RAID controller, which uses the > amr driver. They upgraded to larger, 15k rpm ultra 320 disks (from > smaller 15k rpm ultra 320 disks). They made a backup of their web > root, which is a seperate partition, using dump to a temporary drive, > then swapped in the new disks, installed FreeBSD 7.1, and restored > their webroot to a partition on the new array. > > Does anybody have any insight into what could be going on here? I believe there was a performance regression in 7.1 for SCSI disks. I don't know if the amr driver was affected but the issues should be resolved in FreeBSD 7.2 so you might want to give that a try.
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