On Mon, 14 Sep 1998 13:51:50 -0700, Henry B. Hotz wrote:
> I like your suggestions for avoiding wasted space.  Now a couple of nits:
> 
> Data transfer rate delays are about 2 orders of magnitude smaller than seek
> time and latency delays.  If you're worried about it get another disk and
> use it for swap so swap seeks don't fight with file-access seeks.

I have been well aware that the "performance gain" might have been
negligible but thanks for the clarification.  I was too lazy to go
into the detail.  I should have said it was more of "better than
nothing" kind of "better" ;-)

> >> It makes things look neater under MacBSD, but remember that this is all
> >> imaginary.
> >
> >Not if you are really determined to waste as few sectors as possible.
> >The wasted sectors by misaligned FFS partitions are real.
> 
> I was referring to the speed assumptions made by the FFS algorithms.  The
> space issue is real of course, if small.

Ok, but IIRC the original poster mentioned the unallocated blocks at
the end of a partition.  So, I just assumed that the "optimal" meant
the optimal use of the real estate on the disk surfaces rather than
the optimal performance which FFS's geometry model is clearly not
sufficient to achieve.

> Someone on this list posted a way to get the actual geometry of a SCSI
> drive zone-by-zone.  I imagine you could get a small speed gain by
> arranging for the supposed cylinder boundaries to match up with the actual
> physical ones, but that's probably not possible without substantial
> modifications to several parts of the OS.

If we are really going to do it, a serious rethinking in FFS is in
order.

Cheers,

Ken