From owner-freebsd-scsi Mon Oct 14 08:59:51 1996 Return-Path: owner-freebsd-scsi Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id IAA06005 for freebsd-scsi-outgoing; Mon, 14 Oct 1996 08:59:51 -0700 (PDT) Received: from post.io.org (post.io.org [198.133.36.6]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id IAA05945 for ; Mon, 14 Oct 1996 08:59:28 -0700 (PDT) Received: from rogue.io.org (rogue.io.org [198.133.36.157]) by post.io.org (8.7.5/8.7.3) with SMTP id LAA23369; Mon, 14 Oct 1996 11:58:59 -0400 (EDT) Date: Mon, 14 Oct 1996 11:58:59 -0400 (EDT) From: Brian Tao To: Stefan Esser cc: FREEBSD-SCSI-L Subject: Re: Wonky controller or drive? In-Reply-To: <199610141501.RAA00816@x14.mi.uni-koeln.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@freebsd.org X-Loop: FreeBSD.org Precedence: bulk On Mon, 14 Oct 1996, Stefan Esser wrote: > > Hmm, adding the 7th drive caused problems ??? No, not precisely. This is the history: sd1 was a 4GB Quantum Atlas to begin with. That one died during a power outage about a month ago. I replaced it with a 1GB drive in the meantime. That's still seven devices. I only recently replaced it with a new 4GB drive, since we were running out of room on the 1GB (Web and FTP server logs, mostly). The cable configuration hasn't changed, just that one drive. sd0 and sd1 (1GB boot drive, plus the new 4GB drive) are mounted internally in the PC (50-wire ribbon cable, about 40 cm). The remaining drives are in two daisy-chained external enclosures, total cable length of about 150 cm (two lengths of external cabling, two lengths of internal ribbon cabling), out to the last drive. The internal chain is terminated with jumpers on the Quantum. The external chain has an active terminator plugged into the last enclosure. Each enclosure has its own power supply and fans. One has four bays (three drives) and the other has two bays (two drives). > I guess this is the largest disk capacity that > ever got connected to a single 53c810 ... :) SCSI bus speed isn't a consideration for our FTP server... I just needed the mass storage. :) > I expect this to be caused by either a too > long cable (for the transfer rate) or a problem > with the power supplies. What is the maximum? 6 m or something like that? I should be well within spec. [much helpful description of panic messages deleted... thanks!] > Well, my first guess would be the SCSI cable being > too long (or not good enough) or the peak load on the > power supply being too high. > > You can check the prior by using only slow transfers > (async. or at most 5MB/s sync). If the power supply > is at its limit, then you should be able to cause > failures by increasing the seek rate (ie. do random > seeks with little data actually being transferred). Hummmm... what could I use to do that? Running bonnie repeatedly on the 4GB drive for the random seek tests? I don't think there is a way on the NCR (unlike the Adaptecs) to specify the bus speed or sync/async mode. -- Brian Tao (BT300, taob@io.org, taob@ican.net) Senior Systems and Network Administrator, Internet Canada Corp. "Though this be madness, yet there is method in't"