Out of inodes. SunOS4.0, gripe.

[Charles Hedrick]

In describing how to increase the number of inodes, you have made what
I assume is a typo.  You point at sectors per track and tracks per
cylinder, and say that if either is even, you divide by two.  I think
you didn't say quite what you meant.  In fact what you want is for the
product to be even.  So in fact you need to fake things if both are
odd, which isn't quite what you said.

The primary goal of the operation is to increase inodes in the
partition by getting more cylinder groups.  This means you have to
decrease cylinders per cylinder group.  There is an argument to mkfs
to specify cylinders per cylinder group.  However you can't specify
anything smaller than 16 unless sectors per cylinder is even.  Of
course sectors per cylinder is (sectors per track) * (tracks per
cylinder, i.e. number of heads).  If that number is even, you can use
8 cylinders per cylinder group.  If it is a multiple of 4, you can use
4 cylinders per cylinder group.  Etc.  I agree with you that lying
about the geometry is the right way to proceed.  Rather than divide by
two, I simply decrease the number of sectors per track by one.  In
your case, sectors per track is 83, and there are 15 heads.  83 * 15 =
1245 sectors per cylinder.  This is odd.  By reducing sectors per
track to 82, you get 1230, which is even.  You can now specify 8
cylinders per cylinder group, and get double the number of inodes.  If
you need even more inodes, you could use 80 sectors per track, which
gives 1200 sectors per cylinder.  This is a multiple of 16, so you
should be able to specify any power of two for cylinders per cylinder
group.