Subject: Re: iSCSI Target Reset

From: "John Hufferd" <[email-masked]>
Date: Mon, 23 Apr 2001 14:34:21 -0700

Absolutely not,  Why would we think that impacting 32 different other
initiators is an OK thing to do.  By the way there are lots more Initiators
possible with FC on Shark, and would hope that there would be even more
with iSCSI.

I have been told that these large Storage Controllers do not support Target
Reset today.  So I see no loss in not supporting such an item in iSCSI
especially since many Initiators will be beyond even the distances and
mischief that is possible with FC.

.
.
.
John L. Hufferd
Senior Technical Staff Member (STSM)
IBM/SSG San Jose Ca
(408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
Internet address: [email-masked]

Santosh Rao <[email-masked]>@ece.cmu.edu on 04/23/2001 01:24:02 PM

Sent by:  [email-masked]

To:   [email-masked]
cc:
Subject:  Re: iSCSI Target Reset

"Dillard, David" wrote:
>
> When will STORPORT be generally available?  The latest STORPORT document
> that I found on the MS web site is version 0.6a, dated March 18, 2001.
> Given this it seems like STORPORT might not be available soon.  In that
case
> do you know what happens with the current drivers?  Are we going to be
> telling customers that if they want to use iSCSI and NT clustering they
have
> to update to Whistler?

[One would hope that this list does not turn into a Microsoft
release/product discussion mailing list (?) ]

Without going into specifics of A certain O.S., does it suffice to
require that iSCSI not break existing legacy SCSI applications ?

If the above is a valid requirement, then, knowing that legacy
applications continue to use SCSI-2 Reserve/Release and the target reset
as a mechanism of breaking SCSI-2 reservations, should'nt iSCSI continue
to support the target reset ?

- Santosh

---

From: Santosh Rao <[email-masked]>
Date: Mon, 23 Apr 2001 17:53:01 -0700

Such large targets are also capable of features like target zoning which
can restrict the impact caused by host[s] using the target reset.Host
environments that deploy such forms of recovery are zoned to avoid
disrupting I/O activity from other OS'. This restricts the scope of
error recovery while not breaking legacy apps dependent on target reset. 

I'm aware of at least 2 high end FC arrays (one being the EMC Symmetrix)
[and several mid-range arrays] that do support the target reset. 

- Santosh

---

From: Mark Mokryn <[email-masked]>
Date: Tue, 24 Apr 2001 11:08:40 +0300

Shark does indeed support Target Reset. According to the Shark reference
manual, a Target Reset has the effect of performing a LUN Reset on each
LUN surfaced on the port. Interestingly, for FC (and not for parallel
SCSI), Shark surfaces all LUNs on all ports (there are ACLs per LUN), so
I assume a Target Reset has the unfortunate effect of reseting the
entire Shark...

-- 
Mark Mokryn      SANgate Systems Inc.      [email-masked]
Phone: +972-9-8919821                Mobile: +972-54-270030
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