Date: Tue, 20 Jan 2004 14:33:31 -0700 From: "Kenneth D. Merry" <ken@kdm.org> To: Julian Elischer <julian@vicor.com> Cc: SCSI@freebsd.org Subject: Re: CAM//SCSI disk timeouts Message-ID: <20040120213330.GA15900@panzer.kdm.org> In-Reply-To: <400D9B08.70005@vicor.com> References: <400D9B08.70005@vicor.com>
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On Tue, Jan 20, 2004 at 13:18:00 -0800, Julian Elischer wrote: > > > If we are talkign to a raid array and it discovers that it has to > do some maintanance (e.g. declare a physical disk bad or recreate > some data on the fly) it is possible that transactions to the raid > that are outstanding may tak a lot longer than usual. In particular, > we've seen the case where a log entry in teh Raid controller's log > that indicates that a drive has been declared bad, is often accompanied > in FreeBSD with a set of CAM /scsi-disk timeouts > and things degrade from there... > > Where can I find the timeouts in force fo rscsi disks and teh retry > policies? > > I need to compare the theoretical behaviour of FreeBSD CAM with the > theoretical timeouts needed for the raid array, given a disk failure.. You can tweak the timeout and retry count values with the kern.cam.da.retry_count and kern.cam.da.default_timeout sysctl variables. They are also available as loader tunables. Ken -- Kenneth Merry ken@kdm.org
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