Re: iscsi : Async Message "target requests logout".

["Julian Satran" <Julian_Satran@il.ibm.com>]

Due to security reasons we adopted the rule of only one login / TCP
connection. You can't relogin on the same TCP connection.

iSCSI asynchronous messages are not SCSI AENs (although they carry those
too). Support for iSCSI Async. Messages is not optional.

The close connection flavor of the message is the handiest for recovery
(initiator knows when he gets it
that the target will close the target end of it).

I think that the text saying perform a logout - implied also the "implicit"
logout from a login with restart but I will check again.

Julo



Santosh Rao <santoshr@cup.hp.com>@ece.cmu.edu on 29-08-2001 23:08:36

Please respond to Santosh Rao <santoshr@cup.hp.com>

Sent by:  owner-ips@ece.cmu.edu


To:   IPS Reflector <ips@ece.cmu.edu>
cc:
Subject:  iscsi : Async Message "target requests logout".



All,

I've some concerns on the new wording for async messages in rev 07. The
new wording for the async message iscsi event "target requests logout"
reads :

 "2    Target requests Logout. This Async Message MUST be sent on the
same connection as the one being  requested to be logged out.  Initiator
MUST honor this request by issuing a Logout as early as possible, but no
later than Parameter3 seconds.  Initiator MUST send a Logout with a
reason code of "Close the   connection" to cleanly shutdown the
connection.  If the initiator does not Logout in Parameter3 seconds, the

target MAY send an Async PDU with iSCSI event code "Dropped the
connection" if possible, or simply terminate the transport connection."

In the following cases, the initiator may be unable to or may choose not

to use "close the cxn" logout :

1) initiator is only implementing session recovery and is using single
cxn sessions. In this case, it would just perform a session logout
+ re-login [or an implicit session
logout and  re-login by sending another session login
with the same ISID and NULL TSID.]

2) Initiator does not provide support for async messages and chooses to
ignore async messgaes. Async messages are provided for diagnostic
capabilities and differing classes of initiators may have differing
level of diagnostic & recovery support. Simple initiators may just
ignore the async messages as the message is bound to be followed by some

action from the target end. Mandating the responses to async messages
does not allow for this initiator behaviour.

The "close the cxn" flavor of logout or the initiator responses to async
messages must not be mandated, since differing levels of error recovery
support in initiators can result in different behaviours.

Regards,
Santosh

 - santoshr.vcf