RE: Command Queue Depth (was asymmetric/Symmetric)

[Charles Monia <cmonia@NishanSystems.com>]

> -----Original Message-----
> From: Matt Wakeley [mailto:matt_wakeley@agilent.com]
> Sent: Thursday, September 07, 2000 10:25 PM
> To: Jim McGrath; ips
> Subject: Re: Command Queue Depth (was asymmetric/Symmetric)
> 
> 
> Jim McGrath wrote:
> 
> > I agree that BB credit has nothing to do with commands per se, but
> > illustrates the problem we have had with deciding on 
> policies for the
> > distributed allocation of device resources over multiple 
> initiators.  In my
> > postscript I noted that the same problems have arisen on 
> command queue (how
> > many queue slots do you get), with similarly no 
> satisfactory solution.
> 
> So it sounds to me like this distribution of (command) 
> resources across
> initiators is a T10 SCSI issue, and should be solved there, 
> not by each
> individual transport (yesterday FC - which didn't solve it, 
> today iSCSI,
> tomorrow IB or whatever).
> 

Hi Matt:

One thing I got from Jim's note is that SCSI storage devices designs are
carefully tuned. So, behaviors at the transport layer do make a difference
-- especially to cost-driven products.  In my opinion, the IPS community
would be well advised not to ignore these concerns.

Charles
Charles Monia
Senior Technology Consultant
Nishan Systems Corporation
email: cmonia@nishansystems.com
voice: (408) 519-3986
fax:   (408) 435-8385