AIC7902 SCSI aborted command

[Don Bowman]

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.

How can one determine this is a CRC error? Is the reserved ASC/ASCQ
something that would be in e.g. the seagate manual as a vendor
specific thing?