Large disks (was Re: bin/19635: add -c for grand total to df(1))

[Garrett Wollman]

<<On Thu, 6 Jul 2000 13:18:40 +0200, Stijn Hoop <[EMAIL PROTECTED]> said:

> Maybe this isn't the right list to ask, but stepping into this:
> I bought a 30G drive recently, and I was wondering if the 10% 'rule'
> for performance is still really needed. I mean, I lose 3 _gigs_ of
> storage space, and otherwise the performance detoriates? That
> doesn't make sense to me.

Yes.  The efficiency of the hashing mechanism used to lay out new
blocks on the disk depends only on what fraction of the disk is used,
not how much space that represents.  (On the other hand, it is
unlikely that you are significantly stressing the allocator in any
meaningful way.)

If you're concerned about wasted disk space, there's a lot to be
gained by fiddling with the block sizes, bytes per inode, and other
layout parameters.  Your 30-GB disk probably has a zillion cylinder
groups, which is far too many to actually be helpful in disk layout.
When creating a large filesystem, it pays to increase the `-c'
parameter as high as newfs will permit.

-GAWollman




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