Re: aic94xx driver woes continued

[Alexis Bruemmer <alexisb@us.ibm.com>]

On Thu, 2008-03-20 at 16:17 -0500, James Bottomley wrote:
> On Thu, 2008-03-20 at 22:08 +0100, Raoul Bhatia [IPAX] wrote:
> > hi james,
> > 
> > James Bottomley wrote:
> >  > A work around might be to lower the queue depth to say 4 or 8 and up the
> >  > retries (this latter can only be done by altering the SD_MAX_RETRIES
> >  > parameter in include/scsi/sd.h and recompiling).
> > 
> > any suggestions for these parameters:
> > 
> > include/scsi/sd.h:
> >  > #define SD_TIMEOUT              (30 * HZ)
> >  > #define SD_MOD_TIMEOUT          (75 * HZ)
> >  >
> >  > #define SD_MAX_RETRIES          5
> >  > #define SD_PASSTHROUGH_RETRIES  1
> > 
> > shall i alter the timeouts?
> 
> The timeouts can be altered on the fly
> at /sys/class/scsi_device/<device>/device/timeout
> 
> but I'd leave them as is for now ... it wasn't the timeouts that fired.
> 
> > what is a good value for the retries? time it by 2? by 5? by 10?
> 
> I'd up the retries to say 15 and see if that works.
> 
> > moreover, where can i lower the queue?
> 
> echo <new depth> > /sys/class/scsi_device/<device>/device/queue_depth

We have played a lot with the queue depth on this controller.  So far
the best we have done is extended the time before an end device is
eventually dropped.  I am very curious to see what happens in Raoul's
test case.


> 
> James
> 
> 
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