Clarify between decimal bytes and binary bytes

Elliott, Robert (Server Storage) Elliott at
Wed Jul 7 11:06:20 PDT 2010

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Bob Snively championed that back in 2000 during SPC-2 letter ballot. The
conflicting units actually don't appear very often in the T10 standards.
* SPC-4 revision 25 section 3.6.4
* SES-3 revision 2 section 7.3.11 table 95
SBC-3 revision 22 has no remaining uses of binary OR decimal prefixes, so no
longer references IEC 60027.
Rob Elliott    HP ISS Platform Technology - Server Storage
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Kevin D Butt
Sent: Wednesday, 07 July, 2010 11:37 AM
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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