SES -> Generation code changes related to one of the ESPs going down

Raj Divecha Raj.Divecha at dothill.com
Tue Dec 27 09:37:39 PST 2011


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1112271_f.htm">HTML-formatted message</a>

Hi,
This is pertaining to a system that has more than one Enclosure Services
Processes (ESPs).
Now, these ESPs would be running on separate processors and for maintenance
reasons one processor might have to be taken down for some time and that
would make one ESP unavailable for that time.
By definition, the Generation Code has to be updated if anything changes in
the Configuration diagnostic page. If one ESP goes down, technically we can
report that in the Number of ESPs field in the Enclosure descriptor of the
Configuration diagnostic page and thus update the generation code. But this
would lead to some unnecessary processing in the device server as well as in
the application client. I was wondering if the SES specification really meant
to name the field as "Number of Possible ESPs" rather than "Number of ESPs".
We clearly understand the purpose of having the Generation Code and it is to
communicate that some subenclosure or some devices are added or removed that
potentially affects the configuration for an extended time. Devices that are
meant to be a permanent part of a configuration and are added or removed
aren't added/removed to/from the Configuration diagnostic page and thus do
not affect the generation code rather we report the unavailability through
the Element Status Code field.
Thus, my rational behind assuming that the field was rather meant to be named
as "Number of Possible ESPs" is as follows...
1)	N number of ESPs are supposed to be permanent part of a system.
2)	Even if the generation code is updated and the application client
gets its configuration cache refreshed, it isn't going to find any change in
the number of devices in the configuration. This request and response to
update the configuration cache would be unnecessary processing for the device
server and the application client.
I will be implementing related code in the near future and I want to make
sure my implementation is technically correct. Thus, please let me know
whether should I update the Number of ESPs field (and thus the Generation
Code) if one of the ESPs goes down.
Thanks,
Raj



More information about the T10 mailing list