AIC7902 SCSI aborted command

[Scott Long]

Wilko Bulte wrote:
> On Mon, Aug 04, 2003 at 04:10:15PM -0400, Don Bowman wrote:
> 
>>From: Justin T. Gibbs [mailto:gibbs at scsiguy.com]
>>
>>>>After ~200 hours of operation a PC spit out this message:
>>>>
>>>>Copied 18 bytes of sense data offset 12: 0xf0 0x0 0xb 0x0 
>>>
>>>0x0 0x40 0xff 0xa
>>>
>>>>0x0 0x0 0x0 0x0 0x47 0x3 0x8 0x0 0x0 0x0
>>>>(da0:ahd0:0:0:0): WRITE(06). CDB: a 0 40 ff 80 0
>>>>(da0:ahd0:0:0:0): ABORTED COMMAND info:40ff asc:47,3
>>>>(da0:ahd0:0:0:0): Reserved ASC/ASCQ pair field replaceable unit: 8
>>>>
>>>>The system has a single U320 15KRPM seagate 18GB drive in it.
>>>>No other messages are present.
>>>
>>>This means that the target saw a CRC miscompare on a packet.  CAM
>>>retried the command and it succeeded.  CRC errors are not unheard
>>>of in U320 configurations, but at only 200 hours of load, that is
>>>a little too often for comfort.
>>>
>>>I believe you mentioned before that you were using an extremely
>>>short cable in one of your configurations.  Be aware that there
>>>is a minimum cable length suggested by the SCSI spec.  This
>>>varies depending on the capacitance rating of your cable, but
>>>the shortest length allowed is 10cm (cables with less capacitance
>>>need larger spacing).  If your cable is shorter than this, you might
>>>consider trying something longer.
>>
>>Me & my trusty ruler re-measured the cable, and straightened out,
>>it is 10.4" tip to tail, which matches the spec. I was foolishly
>>thinking of the folded length.
> 
> 
> It isn't too folded I hope? In the sense that you sometimes
> find flatcables stashed in miniscule cutouts in cases etc. Not
> too good for signal integrity either.
> 

Except in cases where you need to slip through a tight slot and only a
flat cable will do, the new-fangled round u320 cables are superior to
their flat counterparts.

Scott