From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tokarev Subject: Re: [OT] best tape backup system? Date: Wed, 23 Feb 2005 00:52:32 +0300 Message-ID: <421BA9A0.5010402@tls.msk.ru> References: <200502221651.j1MGp1922341@www.watkins-home.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: <200502221651.j1MGp1922341@www.watkins-home.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Guy wrote: > I have NOT been able to share a SCSI cable/card with disks and a tape drive. > Tried for days. I would get disk errors, or timeouts. I corrected the > problem by putting the tape drive on a dedicated SCSI bus/card. I don't > recall the details of the failures, since it has been well over a year now. > But I do know I only had problems while using the tape drive and the disks > at the same time. Like, during a backup. The disks were happy while the > tape drive was idle. I also swapped parts, it had no effect. I assumed > Linux does not like to share SCSI. There may be various reasons for this, and i think all of them are related to hardware only, esp. to the SCSI bus. Eg, some modern disk drives don't understand SE mode anymore, so can't be plugged into an scsi bus with at least one SE device. On the other hand, it was qutie common for esp. old tapes to NOT understand LVD mode. Obviously you can't mix that sort of devices on the same bus. I guess the bus where you drives are is in LVD mode while tapes works in SE mode... BTW, I've seen quite modern tape drive with an old scsi connector (I don't even remember anymore how it's called -- the one which looks pretty like an IDE connector but a bit wider and with more (80?) pins; with max speed of 20Mb/sec aka 10MHz or so) inside the case and with an adaptor for current 68pin scsi connector standard. Obviously it works in SE mode only (that bus worked in that mode only). Don't remember which vendor that drive was... /mjt