[5954] in linux-scsi channel archive
Re: delay after SCSI bus reset
daemon@ATHENA.MIT.EDU (Matthew Jacob)
Sun Feb 21 05:34:01 1999
Date: Sun, 21 Feb 1999 02:30:21 -0800 (PST)
From: Matthew Jacob <mjacob@feral.com>
Reply-To: mjacob@feral.com
To: Richard Waltham <dormouse@farsrobt.demon.co.uk>
Cc: Kurt Garloff <K.Garloff@ping.de>,
Linux SCSI list <linux-scsi@vger.rutgers.edu>
In-Reply-To: <001f01be5d54$7e169dc0$0400a8c0@arak>
> >The answer is to have a SCSI middle layer that defers (re)queueing
> >commands to the HBA's until after a (tunable) delay has occurred.
> >Strictly speaking the delay is a per-target value since the amount of
> >recovery time after a reset until a target can actually accept selection
> >is not covered by the SCSI specification.
> >
> >
>
> Section 5.7 of the SCSI 2 spec mentions a value of 250ms for a hard reset to
> selection time - but its only a recommendation.
>
I don't have my SCSI spec in front of me- this may simply be the
propagation of the recommended selection timeout of 250ms - if initiators
will wait up to 250ms then try and be ready before that time has elapsed.
But there's no guarantee past SCSI bus reset whether a device will respond or
not.
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