Date: Wed, 6 Oct 1999 14:43:36 -0700 (PWT) From: Matthew Jacob <mjacob@feral.com> To: Gerard Roudier <groudier@club-internet.fr> Cc: "Justin T. Gibbs" <gibbs@narnia.plutotech.com>, Vadim Belman <voland@plab.ku.dk>, scsi@FreeBSD.ORG Subject: Re: 'Unexpected busfree' Message-ID: <Pine.LNX.4.04.9910061441420.1525-100000@feral.com> In-Reply-To: <Pine.LNX.3.95.991006231903.499A-100000@localhost>
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> The behaviour of those old peripherals does not look that bad to me, > even if some better one may be possible. > > Since SCSI parity bit mostly protects against single bit error, a SCSI BUS > that experiences oftently SCSI parity errors has some non negligible > probability to lead to undetected data corruptions. So, dropping the BUS > is such a situation is quite acceptable and warn user about possible BUS > problem, provided that the unexpected bus free condition is loudly > reported to him by the system. > > The SCSI device may elect to try to recover by restoring the saved > pointers. This may look more user-friendly but will increase the risk of > silent data corruption as seen by user. May-be the most clever device > decision should be to try asap to complete the command with appropriate > sense data, but just dropping the BUS seems to me a more safe device > behaviour than trying to recover from a SCSI parity error. I agree with you. An unexpected bus free shouldn't be a problem. It does make it difficult to use the correct sense key for the next command though as an unexpected bus free is not an indicator to run Request Sense. -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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