On Wed, Oct 27, 2010 at 06:19:32PM +0200, Mikulas Patocka wrote: ... > Requeuing forever is dangerous anyway, a device returning QUEUE_FULL > constantly could deadlock the system. Question: is it better to risk a > deadlock with a broken device or to risk a false timeout under high load? > --- I don't know --- maybe there are valid cases where the device is > returning QUEUE_FULL for long time (some raid reconfiguration?) ... do you > know about them? This was a problem in multi-initiator SCSI systems and I'm guessing also an issue for FC SAN. Multiple hosts "compete" for filling the device's available command slots. If all hosts used available queue_depth (say 32 commands) and device only supported 64 commands at a time, then the 65th command from host #3 might get QUEUEFULL status back. I'm not sure what the difference is to BUSY status. Wikipedia suggests "QUEUE_FULL" is a hint that the device is already processing commands from the same initiator. hth, grant -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
