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Conference turris::digital_unix

Title:DIGITAL UNIX(FORMERLY KNOWN AS DEC OSF/1)
Notice:Welcome to the Digital UNIX Conference
Moderator:SMURF::DENHAM
Created:Thu Mar 16 1995
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:10068
Total number of notes:35879

9030.0. "diskconfig" by NETRIX::"[email protected]" () Tue Mar 04 1997 16:27

Hi all,

Has anyone noticed that the conversion from blocks to Megabytes is wrong on
the "diskconfig" utility in DU V4.0.

Thus if you work in Megabytes and commit your configuration. Then look at
the disklabel your partitions will be about 5% smaller than you wanted them.

Cheers

Lance.

[Posted by WWW Notes gateway]
T.RTitleUserPersonal
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9030.1Some people think 1 = 1.048576SMURF::KNIGHTFred KnightTue Mar 04 1997 18:2126
Oh NO, marketing does it again.

This is probably the old computer Mega-bytes vs. Marketing Mega-bytes.
Marketing Mega-bytes is also known as Metric Mega-bytes.

Does a Mega-byte = 1 Million bytes = 1,000,000 bytes?
or
Does a Mega-byte = 1 Million bytes = 1,048,576 bytes?

If you are familiar with the real world of Kilometers and Kilograms
and all those other measurements for length, and mass, and all that
other stuff, then you might assume that 1 million = 1,000,000.  If
you also assume that 1 character = 1 byte, then a disk with room
for 1 million bytes should store a 1,000,000 character document.

Notice that most (if not all) disk vendors use the marketing Mega-byte
for the measurement for their disks.  A 135Mb disk I have will hold
a document containing roughly 135,000,000 characters (or bytes).  It
actually holds exactly 134,217,728 bytes (which if you divide by
1048576 - a computer mega-byte, makes 128Mb).

So, I guess that just goes to prove that in marketing 128 = 135 (or
1 = 1.048576).  I suppose it's a miracle that marketing people and
computer people ever agree!

	Fred
9030.2DECWET::MARTINTue Mar 04 1997 18:4211
And if you want to get even more confusing than 1,000,000 == 1048576, then take
a look at 3 1/2 inch floppy disks.  You know, the standard floppy disk of today,
which holds "1.44 MB"?  Well, it will actually hold 1474560 bytes.

Lessee, 1474560 / 1000000 = 1.47 MB.  Nope, that ain't it.
        1474560 / 1048576 = 1.41 MB.  Nope, that ain't it either.

	1474560 / 1.44 = 1024000.

That's right, a "floppy disk megabyte" is 1024 * 1000.  Somebody decided to
combine the 2^10 and the 10^3 figures.  Aieeee!
9030.3Will be fixedNETRIX::"[email protected]"Chip MaurerFri Apr 04 1997 17:046
Yes. The conversion of blocks -> megabytes is wrong
in 4.0 version of diskconfig. This will be fixed in
4.2 (Steel) release, as well as a significant change
to the interface.
[Posted by WWW Notes gateway]
9030.4SMURF::DENHAMDigital UNIX KernelFri Apr 04 1997 18:192
    Come on! Fix it in V4.0D. Why wait almost a year for Steel! We have
    a real development release open now....
9030.5You're rightNNTPD::"[email protected]"Chip MaurerWed Apr 16 1997 18:317
Up to now, my emphasis on diskconfig had been Steel.

I've been going over the QARs and will work on getting
as many QAR fixes into 4.0D as I can (including the
megabyte fix).
[Posted by WWW Notes gateway]