SES-2 attached enclosure services and reset conditions

Elliott, Robert (Server Storage) elliott at hp.com
Tue Nov 16 07:33:02 PST 2004


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <elliott at hp.com>
*
A standalone SES-2 enclosure services process can interpret the I_T
nexus loss, logical unit reset, hard reset, and power on conditions
defined in SAM-3 as needed.

An attached SES-2 enclosure services process (e.g. attached to a FC disk
drive via an SFF-8067 ESI interface), however, is not exposed to those
conditions (except for power on):
a) I_T nexus loss: SES doesn't know which initiator port is
sending/receiving the diagnostic pages, and doesn't know when
logins/logouts occur to the drive
b) logical unit reset: SES doesn't know about the drive's logical unit
resets
c) hard reset: SES doesn't know about the drive's hard resets
d) power on: SES responds to its own power supply

For the most part, this is irrelevant, because the only condition
mentioned by SES-2 is "power on."

However, the Download Microcode diagnostic page proposed in 04-377 would
be sensitive to certain conditions if it mimics WRITE BUFFER command
behavior:
a) mode 6h: stop using new microcode after hard reset (or power on)
b) mode 7h: start using new microcode after hard reset (or power on), or
possibly earlier
c) mode 6h or 7h: discard partially downloaded microcode after logical
unit reset or I_T nexus loss (or hard reset or power on)

I don't think forwarding I_T nexus loss would be practical (it would
also require forwarding I_T nexus creation status, and might imply
tagging every diagnostic page with an initiator port identifier).
However, we could define a diagnostic page to forward logical unit
resets and hard resets if that made sense.

What approach should 04-377 take?
1) For standalone SES, follow the WRITE BUFFER conventions.
   For attached SES, just use power on:
  mode 6h: stop using new microcode after power on
  mode 7h: start using new microcode after power on, or possibly earlier
  mode 6h/7h: discard partially downloaded microcode after power on

2) For both standalone SES and attached SES, just use power on:
  mode 6h: stop using new microcode after power on
  mode 7h: start using new microcode after power on, or possibly earlier
  mode 6h/7h: discard partially downloaded microcode after power on

3) For standalone SES, follow the WRITE BUFFER conventions.
   For attached SES, define a new diagnostic control page to specify
hard reset and logical unit resets. Either the drive and/or the
application client could send that page.
   Make the Download Microcode page work like this:
  mode 6h: stop using new microcode after hard reset (or power on)
  mode 6h/7h: discard partially downloaded microcode after logical unit
reset (or hard reset or power on)
  mode 7h: start using new microcode after hard reset (or power on)

4) For both standalone and attached SES:
  mode 6h: drop this mode
  mode 7h: start using new microcode after returning the Download
Microcode Status page
  mode 7h: discard partially downloaded microcode after power on

5) Other combinations are possible.


-- 
Rob Elliott, elliott at hp.com 
Hewlett-Packard Industry Standard Server Storage Advanced Technology 
https://ecardfile.com/id/RobElliott 
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