Date: Mon, 20 Sep 2004 18:38:50 -0400 (EDT) From: Charles Sprickman <spork@bway.net> To: "Justin T. Gibbs" <gibbs@scsiguy.com> Cc: freebsd-scsi@freebsd.org Subject: Re: backplane identification Message-ID: <Pine.OSX.4.61.0409201833430.3093@oof.local> In-Reply-To: <614E593AFE91BAF560A42D5D@aslan.scsiguy.com> References: <Pine.OSX.4.61.0409151814370.933@oof.local> <614E593AFE91BAF560A42D5D@aslan.scsiguy.com>
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On Thu, 16 Sep 2004, Justin T. Gibbs wrote: >> Looking more closely, those backplanes should probably be chained: > > They must be chained if you want the system to behave correctly. The > maximum parallel SCSI stub length is ~2in. which I'm sure is shorter > than your backplanes. Interesting. Saturday we went in to replace all 4 18GB drives with 36GB models. While I was in the box, I recabled so that the chain went in one backplane, and then to the other with a seperate cable. Also put a terminator on the second backplane's "end" of the chain. With the terminator on, no drives were found by the controller. With the terminator removed, 4 drives showed up, but one would always show a sync rate of 80MB/s vs 160MB/s on the others. So something is obviously wrong. We ended up just using the one backplane, mirroring two drives and putting a third in as a hot spare. I wonder if perhaps the whole mess is not new enough to support UW SCSI @ 160MB/s? Last question... Are the layouts of these SCA backplane cards at all standardized? I'd gladly swap these out for anything that included docs and is known to work when chained together. We can find no identification on these things. This is a 2U box; each backplane stacks three drives and is secured to the drive cages with a screw on each corner. Thanks, Charles > -- > Justin > >
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