RE: iSCSI question

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

Session recovery means just creating a NEW session and forgetting about all old commands.
It is the last resort recovery where everything else fails and as such it is the most basic function - that anybody has to have.

Julo

Shahram Davari <Shahram_Davari@pmc-sierra.com> 08/07/2002 06:43 PM

To:        Julian Satran/Haifa/IBM@IBMIL         cc:        ips@ece.cmu.edu, owner-ips@ece.cmu.edu         Subject:        RE: iSCSI question

Julian,
 
To start a new session you need to start new connections and you need to support
the PDU recovery. So how is that a subset of PDU and connection recovery?
 
 
-Shahram
 
(I will explain the detailed clarity issues in another email)
-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Wednesday, August 07, 2002 11:34 AM
To: Shahram Davari
Cc: ips@ece.cmu.edu; owner-ips@ece.cmu.edu
Subject: RE: iSCSI question


Session recovery is in fact leaving all recovery to SCSI - it drops everything and creates a new session. 
As for you comment on the clarity of chapter 5 at this stage it makes sense to be either specific 
or keep this type of comment out of this context. 

Julo

Shahram Davari <Shahram_Davari@pmc-sierra.com> 08/07/2002 06:09 PM

To:        Julian Satran/Haifa/IBM@IBMIL        cc:        ips@ece.cmu.edu, owner-ips@ece.cmu.edu        Subject:        RE: iSCSI question

Julian, 
  
Thanks. I have read that section but it is not very clear. 
  
I also agree that Connection recovery requires everything in command recovery. 
But what about session recovery? isn't it a superset of both connection and command recovery? 
  
Yours, 
-Shahram 
-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Wednesday, August 07, 2002 11:03 AM
To: Shahram Davari
Cc: ips@ece.cmu.edu; owner-ips@ece.cmu.edu
Subject: Re: iSCSI question


Sharam, 

You may want to go over the recovery chapter. 
It has detailed answers to all your questions. 
The superset/subset is based on functions you need for the next level. 

Session recovery drops real recovery to SCSI. 
Command recovery recovers from individual command errors without 
changing connection and the highest enable you to switch to a new connection and 
continue commands there. 

2 requires everything in 1. 

Julo

Shahram Davari <Shahram_Davari@pmc-sierra.com> Sent by: owner-ips@ece.cmu.edu 08/07/2002 05:17 PM

To:        ips@ece.cmu.edu       cc:               Subject:        iSCSI question

Hi,

I have a question regarding the hierarchy of error recovery.
Section 6.13 mentions the hierarchy as:

2: Connection recovery
1: Digest failure recovery
0: Session recovery

And it states that the higher levels are a superset of the
lower levels and that the level of complexity increases from 0->1->2.

Couple of questions:

1) How is digest failure recovery done? by retransmission of PDUs?
2) Why is the connection recovery a superset of session recovery
and more complex?
3) It seems to me the order should be:

2: Session recovery
1: Connection recovery
0: Digest failure recovery


I appreciate any insight.

Thanks,
-Shahram