Subject: Re: The thorpej_scsipi branch
To: None <>
From: Matthew Jacob <>
List: tech-kern
Date: 12/28/2000 15:59:05
> SCSI disks typically can take a queue of 16-32, Fibre-Channel are usually
> 64.  These are fixed-length queues, so if there are multiple initiators
> they are shared between the initiators.
> RAID boxes are usually broken:  64-256 tags, but these are shared
> among all the LUNs, so if you have 64 commands outstanding on each
> of LUNs 0..4, you have no tags available for LUN 5 if you ever want
> to send it a command.  You can get a QFULL condition with no outstanding
> commands in that case.
> What Jim Kahn recommends it to run until you get QFULL, set that as
> the limit, then after 1m clear the limit. 

Yeah, I recommended something like Jim's idea a while back- I think I said 30
seconds. It adds a bit of hysteresis to Bob Snively's way of doing stuff.