Date: Mon, 05 Apr 2010 13:34:52 -0700 From: Matthew Jacob <mj@feral.com> To: freebsd-scsi@freebsd.org Subject: Re: adding a "retry command after a delay" error Message-ID: <4BBA496C.4040908@feral.com> In-Reply-To: <4BB98522.6000704@FreeBSD.org> References: <1269900407.00235175.1269888603@10.7.7.3> <4BB98522.6000704@FreeBSD.org>
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On 04/04/2010 11:37 PM, Alexander Motin wrote: > Matthew Jacob wrote: > >> This is something I whipped up for dealing with some >> active/active-after-failover-time systems. I wanted to have a general >> facility to say of an ASC/ASCQ- retry the command, but after a period of >> delay. >> >> Wonder if anyone had comments? >> http://people.freebsd.org/~mjacob/delay_diffs.txt >> > I am not SCSI expert yet, but it seems OK for me. But I see two related > questions there: delay time and number of retries allowed. > > Most of peripheral drivers now AFAIR ask to do only few (2-5) retries, > so if delay will be short - it may give up too early, but long delay > will probably reduce performance. > > I've been doing some rethinking about this. It really is the devq that I want to have stopped and retried with a timeout- not the entire sim. Your point about periph drivers is well taken, and I thought about just capturing this one in da, but it turns out that both sg && pass have the same issue, hence the notion of generalizing it. The sim change is working for the Panasas guys right now, but that's just a bandaid. I'll think some more about this one. Thanks for the comments!
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