Clarify between decimal bytes and binary bytes

Elliott, Robert (Server Storage) Elliott at
Wed Jul 7 13:27:32 PDT 2010

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SPC-4 uses binary units in an EXTENDED COPY command-related TRANSFER COUNT
field (see pg 324 table 206).
SES-3 uses binary units to report non-volatile cache sizes (see pg 100 table
SBC-3 uses binary units when discussing the addressing limits of READ(6) (see
pg 99 note 10).  I thought we deleted that note, but it's still there; we
should consider obsoleting READ(6) and WRITE (6) entirely, which would take
care of that case.   If the note remains, then a normative reference to IEC
60072 is needed.
Rob Elliott    HP ISS Platform Technology - Server Storage
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Knight,
Sent: Wednesday, 07 July, 2010 2:26 PM
To: Kevin D Butt; t10 at
Subject: RE: Clarify between decimal bytes and binary bytes
I can't find any MB, Mb, MiB, or any other such similar unit used in SPC or
SBC.  Every unit that is used is very clearly defined.
I'll be interested to see exactly what it is you are proposing to un-confuse.
I agree marketing literature often has a problem in this area, but we don't
use marketing style language in the T10 standards.
	      Fred Knight
From: Kevin D Butt [mailto:kdbutt at]
Sent: Wednesday, July 07, 2010 12:37 PM
To: t10 at
Subject: Clarify between decimal bytes and binary bytes
I believe that the time has come to clear up confusion in the industry about
the units used in T10 standards.  There should be a clause added in each of
the standards describing the difference between decimal bytes (e.g., MB =
10^6) and binary bytes (e.g., MiB = 2^20).  There has been this definition in
IEC for since Dec 1998.
I hesitate to bring in a solo proposal to modify SSC-4 or even SPC-4 when
this issue should apply to all standards.
Does anybody disagree that T10 should clarify the units being used in our
What is the preferred manner in which we should proceed to make sure this
clarification is added to each standard?
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at

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