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From: mangler@csvax.caltech.edu (Don Speck)
Newsgroups: comp.sys.sun
Subject: Re: Fuji inode problems
Message-ID: <8812171837.AA00552@csvax.caltech.edu>
Date: 30 Dec 88 00:36:08 GMT
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Original-Date: Sat, 17 Dec 88 10:37:07 PST
X-Sun-Spots-Digest: Volume 7, Issue 78, message 1 of 10

In article <8811172007.AA28870@amos.ling.ucsd.edu> you write:
>The problem of not being able to make enough inodes with fuji 23XX drives
>and Xylogics controllers is due to a bug with mkfs.

It is a design limitation of the BSD Fast Filesystem:  each cylinder group
contains a fixed-size bitmap (2048 bits) for inode allocation.  4.3T
replaces it with a variable-sized bitmap, which is not backward compatible
(and cannot be).  You'll know it when Sun picks up this change.

The Fast Filesystem was designed when disks had 32 sectors per track.
Cylinders hold more these days.  This should have been predictable...  but
up through at least SunOS 3.2, there wasn't even support for filesystems
larger than 512 megabytes.	(SunOS 3.5 supports 2048 MB).

The workaround, reducing the cylinder group size, is disallowed on some
drives by the requirement that a cylinder group be an integral multiple of
the filesystem blocksize.  You can work around this by formatting with a
different number of spare sectors per track.