Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!sun-spots-request
From: jms@tardis.tymnet.com (Joe Smith)
Newsgroups: comp.sys.sun
Subject: Re: Newfs under SunOS4.1 reports file system sizes incorrectly
Keywords: SunOS
Message-ID: <9843@brazos.Rice.edu>
Date: 11 Jul 90 02:50:50 GMT
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X-Sun-Spots-Digest: Volume 9, Issue 256, message 14

In article <9702@brazos.Rice.edu> ehrlich@psuvax1.cs.psu.edu (Dan Ehrlich) writes:
>/dev/rid000h:   159900 sectors in 130 cylinders of 15 tracks, 82 sectors
>        81.9MB in 9 cyl groups (16 c/g, 10.08MB/g, 4608 i/g)
>Using my trusty TI-55-II calculator to compute (159900*512)/1048576 yields
>a result of 78.076172MB.  Even worse 9g * 10.08MB/g = 90.72MB, not 81.9MB.

159900 * 512 = 81,868,800 = 81.9*10^6 bytes
16 cyls * 15 tracks * 82 sectors * 512 bytes = 10,076,160 = 10.08*10^6 bytes
130 cyls / (16 cyls/group) = 8.13 groups, must round up to 9 cyl groups

Given that 1M = 1,000,000 those numbers are accurate.

A lot of vendors are using the convention that "1 megabyte" of memory is
exactly 1,048,576 bytes, but "1 megabyte" of disk is 1,000,000 bytes.
(It's more impressive on the sales literature to say that you sell an 81
megabyte drive instead of a 78 megabyte drive.)

Joe Smith (408)922-6220 | SMTP: jms@tardis.tymnet.com or jms@gemini.tymnet.com
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