Re: [PATCH] 2.5.65, cciss_scsi, scsi error handling

[Mike Anderson <andmike@us.ibm.com>]

Cameron, Steve [Steve.Cameron@hp.com] wrote:
> Anyway, I talked this (doing aborts and device resets) 
> over with the firmware guys here, they seemed be of the 
> opinion (off the top of their heads) that aborting commands and 
> so on in the face of timeouts generally tends to make things worse, 
> not better, but said it wouldn't really hurt.  (especially I was 
> worried about i/o the array controller was doing  to disks on the 
> same bus as the tape drive, disks of which linux knows nothing.)
> 

The key thing the SCSI mid needs is the command canceled to ensure that
the LLDD will not reference the scsi_cmnd anymore. Secondary it would be
nice if the BDR got the device sane again, but the probability is low
in response to a timeout that this would be the case.

> Hmm.  If the tape drive were set off line, I wonder could I hot
> plug it to get it back?
> 
> e.g. 
> echo scsi revmove-single-device 0 0 0 0 > /proc/scsi/scsi
> (physically hot unplug tape drive)
> echo rescan > /proc/scsi/cciss1/1
> (physically hot re-plug tape drive)
> echo rescan > /proc/scsi/cciss1/1
> echo scsi add-single-device 0 0 0 0 > /proc/scsi/scsi

If the device is ok and all you want is to set the online flag you
can:

echo 1 > /sys/bus/scsi/devices/0:1:15:0/online

YMMV :-).

-andmike
--
Michael Anderson
andmike@us.ibm.com