Subject: Re: IscsiSessionStatsEntry MIB OBject contents

From: "Thomas McSweeney" <[email-masked]>
Date: Wed, 9 Jan 2002 17:44:38 -0500

Gwendal,

Login PDU and Login Response PDU are not counted in iscsiSsnRspPdus or
iscsiSsnCmdPdus because the session is not instantiated until full feature
phase (after Login Response).  There are separate counters for Login
attempts - see the ...LoginStatsEntry definitions.  All other PDUs are
counted, including Data In and Data Out.  I suppose we could discuss
whether Logout and Logout Response should be counted, since they have
separate counters in the MIB as well (see the ...LogoutStatsEntry
definitions).

As for the Data Octet counters, the easiest interpretation is that it
refers to all octets in all PDU Data Segments.  I think the count will be
most useful if it counts only the bytes of data actually read from or
written to the SCSI device (e.g., it includes only the Data Segments of
Data Out and Data In PDUs).  However, I suspect that the sum total of all
other PDU Data Segments will be so small compared to the Data Out and Data
In that it would not hurt to lump those in.

Tom McSweeney
iSCSI Development, Storage Systems Group, IBM
Email: [email-masked]
Phone: (USA) 919-254-5634  (tie line: 444-5634)
Fax:   (USA) 919-254-0391  (tie line: 444-0391)

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From: Gwendal Grignou <[email-masked]>
Date: Thu, 10 Jan 2002 08:09:51 -0800

Thomas,

I think the definition of MIBs fields should be more precise, so that all 
initiators and targets will store the same information, to allow useful 
comparison.

My comments inline :
> phase (after Login Response).
I don't see why we should not count them.
Within the session object, you have connection objects, each of them with 
"iscsiConnectionAttributesEntry". One of the fields of this sequence is " 
iscsiCxnState", which can be "login",... So as soon as a connection is 
established at TCP level, the connection object (and the session object it 
belongs to) should be instantiated.
> There are separate counters for Login
> attempts - see the ...LoginStatsEntry definitions. 
Those counters do not count the PDUs exchanged between initiator and target, 
but store the result of each login attempts.
> All other PDUs are

> In that it would not hurt to lump those in.
Well, to have a clear definition would ensure the counters for a given 
session have the same value on both the target and the initiator.

Gwendal.