*BSD News Article 62160


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From: bad@flatlin.ka.sub.org (Christoph Badura)
Subject: Re: SCSI problems performing writes to FAST SCSI-2 drives
Date: Thu, 15 Feb 1996 19:35:21 GMT
Message-ID: <DMu12y.ApB@flatlin.ka.sub.org>
References: <4fqnbb$f7v@viking.ucsalf.ac.uk> <4fr9rr$t4i@atlas.uniserve.com>
Organization: Guru Systems/Funware Department
Lines: 37

In <4fr9rr$t4i@atlas.uniserve.com> tom@uniserve.com (Tom Samplonius) writes:

>In article <4fqnbb$f7v@viking.ucsalf.ac.uk>, mark@ucsalf.ac.uk says...
>>The write falls over with the following on VTY2:
>>
>>ahc_scsi_cmd0: more than 256 DMA segs
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>>sd0: oops not queued
>>biodone: buffer already done
>>init died (signal 0, exit 1)
>>
>>I have been occasionally to get past the partition write, but it mentions it
>>can't mount swap and then fails to make the filesystems.
>>This also happens with an IBM DFHS S2F 2Gb FAST SCSI-2 drive. It happens with
>>a 1542C, 1542CF, AHA 2940 controller and on two different machines 100MHz 
>>Pentium and non PCI DX2 66MHz. Same problem, but different number of DMA segs on the 
>>1542 (less SCB's??.) With a DEC DSP5200S 2Gb SCSI-2 (not FAST) I have no problems
>>at all on either machine with any SCSI adapter. I'd really like a FAST drive though.
>>Any ideas what this could be?

>  Termination?  Cable?

No. The drivers are complaining that they need more scatter-gather
segments for the operation then fit in a single CCB.  Yes, the 1542
doesn't support as many scatter-gather segments as the 2940.

I the ahc driver thinks it needs more then 256 segments for a single
request is beyond me, though.  That would mean you are handling it a >
1MB (256 * 4KB per page) request, which is a bit to large for a partition
table.

-- 
Christoph Badura	bad@flatlin.ka.sub.org

You don't need to quote my .signature.  Everyone has seen it by now.
Besides, it doesn't add anything to the current thread.