The Fast Filesystem has lots of knobs for tuning performance. I don't fully
understand the effect of turning any one of those knobs in one direction or
the other. How many people really do?

In one sense, disk technology has not changed much since Kirk did the work
(we still have platters that spin with heads that seek), however, some
things have changed (e.g. Fast SCSI, Fast & Wide SCSI, Ultra SCSI, IDE,
EIDE, plus disks that spin at 4500, 5400, 7200, and higher RPM), so I
wonder when the last time all the default parameters of FFS were revisited
in light of those things about disk technology that have changed.

Further, given that full understanding of the knobs in FFS is limited, I
wonder:  are there any tools that one can run on a raw disk (or on a
filesystem) that can exercise the disk in some way, possibly analyze the
filesystem if one is present, and then suggest potentially better FFS
parameters, and project the likely performance increase?

Or are FFS's existing defaults already giving us 90% of the theoretical
maximum performace for the general case (and thus such a diagnostic or
exercise program wouldn't really be worth writing)?

	curious,

	Erik E. Fair    fair@clock.org