minfree for large file systems raises question

[Daniel F. Fisher]

In v7n62 frank at morgan.com (Frank Wortner) writes:
> "Thrashing" can occur if the filesystem gets too full. . . BSD "fast"
> filesystem implementations usually reserve the last 10% of available
> space just to insure that this does not happen.

In v7n67 mcvax!ritd.co.uk!mr at uunet.uu.net (Martin Reed) writes:
> I am pondering whether the "minfree" default of 10% makes sense with the
> very large file systems that we are beginning to see (1Gb+).

This raises a very interesting question:

Does the 10% rule of thumb, which is quite ancient (maybe even 6 years old
:-), hold for a 1GB+ file system?  Though it is plausible, it is not
obvious that the point of thrashing should scale directly with the size of
the disk.  Has anyone out there bench marked this?

Daniel F. Fisher
dff at morgan.com