Date: Tue, 6 Nov 2007 09:54:09 -0800 From: "Manjunath R Gowda" <mgowda82@gmail.com> To: "Nico -telmich- Schottelius" <nico-freebsd-performance@schottelius.org> Cc: freebsd-performance@freebsd.org Subject: Re: Performance of disk i/o with 3ware Message-ID: <d0b92eea0711060954i74ca514bu1d236367ec38ffd2@mail.gmail.com> In-Reply-To: <20071106122820.GA28254@schottelius.org> References: <20071106122820.GA28254@schottelius.org>
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On 11/6/07, Nico -telmich- Schottelius < nico-freebsd-performance@schottelius.org> wrote: > > Hello! > > I've the problem that sometimes there are many disk waiting processes > (sysctl -n vm.vmtotal), but systat -vmstat shows da0 and da1 busy with > 0-10%. I woudn't worry about how many are sleeping. But, How long they sleep would be interesting data. I guess that the disk i/o is at about 100%, but wondering why I see > those strange values. Why do you think it should be 100%? Are you running any disk I/O intense application? System Information: > > - Disks are attached to 07:01.0 RAID bus controller: 3ware Inc 9550SX > SATA-RAID > > u0216# uname -a > FreeBSD u0216.nshq.netstream.com 6.2-RELEASE FreeBSD 6.2-RELEASE #0: Wed > Oct 31 14:53:00 CET 2007 root@u0216.nshq.netstream.com > :/usr/obj/usr/src/sys/SMPPAEQUOTA i386 > > => kernel contains 3ware patches from CVS, marked for inclusion in 6.3, > because we've seen many times a freeze on that system before > > - Disks are 10k rpm sata disks. > - Board is a Supermicro X7DB8, processor is a quad core Xeon, > E5345@2.33GHz. > > Anyone an idea, > a) why systat -vmstat shows so small busy values? > b) how to debug it further? You can try experimenting with diffrent I/O loads to make sure that there is a problem before start debugging it. -Manjunath
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