Change count & Route Table clearing

Johnson, Stephen B. Stephen.B.Johnson at lsil.com
Wed Sep 1 06:40:54 PDT 2004


* From the T10 Reflector (t10 at t10.org), posted by:
* "Johnson, Stephen B." <Stephen.B.Johnson at lsil.com>
*
Please see below

-----Original Message-----
From: Subramanian Kuppusamy, Noida
[mailto:subramaniank at noida.hcltech.com]
Sent: Tuesday, August 31, 2004 8:05 PM
To: 't10 at t10.org '
Subject: Change count & Route Table clearing


* From the T10 Reflector (t10 at t10.org), posted by:
* "Subramanian Kuppusamy, Noida" <subramaniank at noida.hcltech.com>
*
Hi,
I am new to this group. I have some basic doubts in Annex-K of SAS 1.1 specs

1. If I correclty understood Changecount value is checked by the intiator
only for the top most Expander or the Hub expander.
   From the specification,Changecount value is incremented in an Expander
device only if it initiates a Broadcast(Change). So if a Broadcast(Change)
is initiated by some Expander somewhere in same SAS Domain, the topmost
expander will just forward the Broadcast(Change). 
  In this case obviously the changecount value of topmost expander is not
changed. Then Why this changecount value check is needed after completing
the configuration of route table?

<SJ> All expanders ChangeCount can be checked using Report General.
For all expanders found with a updated change count, 
the initiator can look at each phy of the expander to understand what has
changed.

2. How the routing table in all the configurable expander devices are
cleared before starting rediscover process for some reason.
   It is ok for a self configuring expander as it may handle with some
internal function. But for other configurable expander devices How the route
table is cleared? 
  Am I missing any SMP Request function meant for this??

<SJ> The initiator should not clear the routing tables at the start of each
rediscover.
This would disrupt current IO or SMP traffic. 
The initiator should only change what route entries that needs to be changed

and leave all table entries that are correct as is. 
 

Any input on this will be helpful

Thanks & Regards
Subra
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org




More information about the T10 mailing list