MFC of "Large set of CAM improvements" breaks I/O to Adaptec 29160 SCSI controller

[Scott Long]

On Apr 29, 2010, at 2:50 AM, Pete French wrote:

>> Thanks. First step successful - I can steadily reproduce problem on
>> CURRENT. raidtest with 200 I/O streams over gmirror of two disks on same
>> channel triggers issue in seconds. Any I/O on channel dying after both
>> disks report "Queue full" error same time. The rest of system works
>> fine. If I preliminarily manually adjust queue depth of one disk -
>> everything works fine. I'll investigate it tomorrow.
> 
> Glad you have managed to dupliate it - the queue depth thing is
> inetersting, what changes did you make ? I can try them here and see
> if they improve the situation on either of my two machines.
> 

For the record, queue-full is a common, expected condition in CAM.  It's not something that should be avoided =-)

Scott