Clarify between decimal bytes and binary bytes

Penokie, George George.Penokie at
Wed Jul 7 12:33:50 PDT 2010

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I agree with Gerry's comment. I also looked in several of the most common T10
standards (SPL, SPC, SAM, SBC) and there is no instance of MB, MiB, or the
four letters "mega" in any of those standards. So unless you can show
specific instances of its use, I don't see why we have to deal with something
that is not used in our standards.
Bye for now,
George Penokie
LSI Corporation
3033 41st St. NW
Suite 100
Rochester, MN 55901
george.penokie at
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Gerry Houlder
Sent: Wednesday, July 07, 2010 1:44 PM
To: T10 Reflector
Subject: Re: Clarify between decimal bytes and binary bytes
I agree with your description of the use of MB versus MiB, but a quick search
of the most common T10 standards show no instance of the use of either
acronym. I'm not sure we should be specifying use of terms that are not
present in T10 standards, but are used in product data sheets.
SAS-2 does use MBps (for Megabytes per second) and correctly defines it as a
decimal entity.
On Wed, Jul 7, 2010 at 11:37 AM, Kevin D Butt
<kdbutt at> wrote:
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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