Date: Thu, 13 May 1999 13:05:11 -0700 (PWT) From: Matthew Jacob <mjacob@feral.com> To: Gerard Roudier <groudier@club-internet.fr> Cc: Chuck Robey <chuckr@picnic.mat.net>, freebsd-scsi@FreeBSD.ORG Subject: Re: IBM scsi drives Message-ID: <Pine.LNX.4.04.9905131259420.27263-100000@feral.com> In-Reply-To: <Pine.LNX.3.95.990513214155.1999A-100000@localhost>
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> > On Thu, 13 May 1999, Matthew Jacob wrote: > > > I've had some reasonable good experiences in some contexts with the IBM > > drives- but they have a wierd property of not working if your host adapter > > negotiates sync speeds before negotiating wide. Make sure these drives > > work for you before you pay! > > If your driver/controller pair assume the SYNC agreement is still valid > after a WIDE negotiation that succeeds, then the IBM drives may well > be quite correct. > > A WIDE negotation that succeeds makes the SYNC agreement go back to > ASYNCHRONOUS. So, a driver that negotiates SYNC before WIDE must assume > WIDE-ASYNCHRONOUS if the target agrees with WIDE transfers. > > By the way, SDTR, then WDTR, then SDTR is correct, but indeed stupid since > both Wide and Sync capabilities are returned in the INQUIRY data. > > The right order for negotiations is, first WIDE (leads to ASYNC if > succeeds), then SYNC. Yes, I agree. But systems and f/w don't always do the right thing. Suns enable sync mode first, and then enable wide. IBM Drive accepts the wide and chokes. It's not that it goes back to Async. It just chokes. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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