Subject: [Ips] MPIO with Persistent Reserve Out/In

From: Ming Zhang <[email-masked]>
Date: Wed, 20 Dec 2006 11:15:44 -0500

Hi All

I can not find this from original rfc or the new guide draft about how
MPIO work with Persistent Reserve Out/In or old Reserve/Release.

In iSCSI, a session is a I_T nexus. With MPIO, then between one
initiator and one target will have multiple I_T nexus. If initiator
setup a reservation via 1st session, can it send out commands like write
via 2nd session? Intuitively, I think it should be able to. But from
SPC, reservation will base on I_T nexus so 2 sessions are 2 different
I_T nexus.

Could anyone help to clarify this? Thanks.

Ming

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From: [email-masked]
Date: Wed, 20 Dec 2006 11:36:54 -0500

> via 2nd session? Intuitively, I think it should be able to.

No - if you want that behavior, use multiple TCP connections in a single
iSCSI session.

> But from SPC, reservation will base on I_T nexus so 2 sessions are 2
> different I_T nexus.

That is how iSCSI behaves - no change to SPC.

Thanks,
--David
----------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 176 South St., Hopkinton, MA  01748
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From: Ming Zhang <[email-masked]>
Date: Wed, 20 Dec 2006 15:36:27 -0500

> No - if you want that behavior, use multiple TCP connections in a single

ok.

> That is how iSCSI behaves - no change to SPC.

yes, i meant with 2 I_T nexus, then base on SPC we can not do it in
MPIO.

But from application point of view, why can not do it with MPIO?

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From: Santosh Rao <[email-masked]>
Date: Wed, 20 Dec 2006 14:39:32 -0800 (PST)

> > No - if you want that behavior, use multiple TCP connections in a single

Or, use persistent reservations instead of SCSI-2 reservations.

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From: Ming Zhang <[email-masked]>
Date: Wed, 20 Dec 2006 17:41:12 -0500

> Or, use persistent reservations instead of SCSI-2 reservations.

PR use a reservation key i thought it is still I_T nexus based? Then
still tight to session?