On 07/13/2009 09:20 AM, Hoot, Joseph wrote:
> Mike,
> Just as an FYI (in case you were most curious about this issue) I've
> narrowed this issue down to something with CHAP.  On my EqualLogic, if I
> disable CHAP, I can't reproduce this issue.
> So I did the following.  I after upgrading to the latest OEL 5.3 release
> of the iscsi-initiator, I could still reproduce the problem.  Therefore,
> I did the following:
> 1) Setup another test environment using the same hardware (physical
> different hardware, but all same firmware, models, etc..)
> 2) presented a new test volume from EqualLogic
> 3) ran the ping test (ping -Ieth2  ping -Ieth3
> 4) I couldn't reproduce the issue.
> 5) I checked what the difference were-- CHAP the only difference.
> 6) So I turned on CHAP authentication to the volume.
> 7) rm -rf /var/lib/iscsi/nodes/* /var/lib/iscsi/send_targets/*
> 8) rediscovered targets (after modifying /etc/iscsi/iscsid.conf with
> CHAP information)
> node.session.auth.authmethod = CHAP
> node.session.auth.username = mychapuserhere
> node.session.auth.password = mypasshere
> 9) ran the same ping test and was able to get iscsi sessions to fail
> within 2 minutes.
> 10) I wanted to prove that CHAP was the issue. So I logout out of all
> iscsi sessions.
> 11) I disabled CHAP on the EqualLogic
> 12) rediscovery targets and re-logged in to the sessions (without CHAP
> authentication)
> 13) ran the ping tests and couldn't break it after 30 minutes.
> 14) added CHAP again and was able to break the sessions within 2
> minutes.
> So definitely something odd with CHAP (my guess, either in open-iscsi
> code or EqualLogic code).  I've asked Roger Lopez, from Dell, to attempt
> to reproduce this in his lab.  He has EqualLogic and Oracle VM Servers.
> Oracle developers that I'm working with don't currently have access to
> an EqualLogic, but they are attempting to reproduce this with their
> iSCSI equipment as well.  I'm going to setup port mirroring on our
> switch and run tcpdumps to see what I can get.

This is strange because CHAP does not come into play in the normal IO 
path. When we login we will do authentication with CHAP, but after that 
succeeds it nevers comes up when doing IO. It would only come up again 
when the session/connection is dropped/disconnected and we relogin. For 
the relogin we will do the CHAP authentication again.

Maybe some memory error where chap values are overwriting some other memory.

There was one recent fix by Dell, where when using CHAP they could 
segfault iscsid. Here is the updated RPM that I am working on for RHEL 
5.4 that has the fix:


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