READ (6), WRITE (6), et al.

Mark Evans Mark.Evans at wdc.com
Wed Dec 8 14:52:03 PST 2010


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Hello,
As capacities in storage devices have increased, there has been much
discussion about how several commands do not have the capability to access
or reflect the new capacities.	For example, READ (6), READ (10), READ (12),
WRITE (6), WRITE (10), WRITE (12), and several other commands can not
address LBAs for storage devices having capacities greater than about 2.2
TB, but there are devices today exceeding this capacity and the trend only
goes up and to the right.  In addition, READ (6) and READ (10) are currently
mandatory commands in SBC-3.  There is even a note in the table listing the
commands that reads, "Application clients should migrate from the READ (6)
command to the READ (10) command and from the WRITE (6) command to the WRITE
(10) command."
I think that, at the very least we should make READ (6) and READ (10)
optional and replace the note with, "Application clients should migrate from
the READ (6), READ (10), and READ (12) commands to the READ (16) command and
|from the WRITE (6), WRITE (10), and WRITE (12) command to the WRITE (16)
command."  I go so far as recommending that all commands incapable of
dealing with greater than 2.2 TB be made obsolete, though I could see
waiting to do this until SBC-4.  Thoughts?  Comments?
Please feel free to call or send an email to me with any comments or
questions that you have about this stuff.
Regards,
Mark Evans
Western Digital Corporation
5863 Rue Ferrari
San Jose, CA 95138
Email: mark.evans at wdc.com



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