FC Tape Presentation of Media Auxiliary Memory

JERMAN,STEVE (HP-Boise,ex1) steve_jerman at am.exch.hp.com
Thu Jul 22 11:28:56 PDT 1999


* From the T10 Reflector (t10 at t10.org), posted by:
* "JERMAN,STEVE (HP-Boise,ex1)" <steve_jerman at am.exch.hp.com>
*
Hi Gene,

The differences between the 'Read/Write Attribute' proposal and the
Application Client Log page would be:

1. Parameter Definitions
This is one of the most important parts of MAM - having standard definitions
so that any host can get, say, 'Tape Length' out of any cartridge or device.
Alternatively the host can define/use application specific parameters.

2. Max Parameter Length
Using the existing Log page format, you're stuck with 256 byte max length
parameters. We would like a bit more flexibility. The proposal also talks
about 16k storage space minimum, so that upwards of 64 parameters. Maybe
you'd like to have bigger
ones, and less of them, given the option?

3. Fixed Parameter Length
Having the first 64 parameters fixed at 253 long (a choice that enables one
whole parameter to be stored in 256 bytes of space, including header, I
expect) is getting very implementation specific.

All in all, we are trying to do a lot more with MAM than the Application
Client Log page proposal allows for, but a Read/Write Attribute command
could provide the functionality that Seagate requires. 

Looks like they may remain separate ... probably worth waiting until I have
the actual Read/Write Attribute proposal and then we can discuss further if
you want.

Steve

-----Original Message-----
From: Gene_Milligan at notes.seagate.com
[mailto:Gene_Milligan at notes.seagate.com]
Sent: 22 July 1999 11:09
To: JERMAN,STEVE (HP-Boise,ex1)
Cc: 'Neil T. Wanamaker'; JERMAN,STEVE (HP-Boise,ex1);
Gerry_Houlder at notes.seagate.com; CRIGHTON,IAN (HP-UK,unix1);
WYATT,STEWART (HP-Boise,ex1); 'T10'; 't11'
Subject: RE: FC Tape Presentation of Media Auxiliary Memory


<<As I mentioned, Dal suggested that having Read/Write Attribute commands
in SPC with the parameters defined per device type would be better than
using a log page and also would extend it's use to
media in a library rather than just devices.>>

     I counter proposed something like that for the Host Attributes
function that Gerry generated and was convinced by the engineers working
the issue that Gerry's method was preferred and involved less modification
of firmware.

Gene



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