RE: iSCSI: Connection replacement

["Venkat Rangan" <venkat@rhapsodynetworks.com>]

Pierre,

There is another aspect to connection replacement - any in progress
data/status transfers on the original connection may now be sent on the new
connection, thus "breaking" the connection allegiance requirementg. If we
allowed retaining the same CID as the failed connection, and sent that along
in the Login of the replacing connection (along with the RecoverId as you
suggest), we could have the target maintain connection allegiance with
respect to the CID (although not with respect to TCP connection). Do you
have a suggestion on how the in-progress I/Os can be handled?

Regards,

Venkat Rangan
Rhapsody Networks Inc.
http://www.rhapsodynetworks.com

-----Original Message-----
From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
Pierre Labat
Sent: Wednesday, January 10, 2001 6:23 PM
To: ips@ece.cmu.edu
Subject: iSCSI: Connection replacement


Julian,


Where
=====
2.10 Login command


Problem
======

In the case where
- the maximum number of connections/session is reached
- the initiator is faster than the target to detect a failed TCP
   connection,

the establishement of a new connection to replace the bad
one will fail.

The Login on the new connection will be rejected by the target
because the maximum number of connections is reached and the target
has not yet detected that there were a failed connection.

In the event of a server adapter failure this problem  will almost
always happen.
As soon as the harware fails, the server open a new connection
using a new adapter. The target will not be fast enough to
realize the connection is bad.


Solution
======

a) in the Login message add a field (RecoverID)  to inform the target
  that this connection is to replace a failed one. The value 0xffff
means
  it is not a connection used to replace an old one.

b) After the login phase, the first message sent to the target on this
   new connection must be a Logout for the failed connection. If not
  the target close the connection.


Regards,

Pierre