Re: Benefits from computing physical IDE disk geometry?

John Bradford
2003-04-18T13:10:36Z

> > Is the basic assumption that lower block numbers are generally located
> > in zones nearer the outside of the disk still true, though? I.E. do
> > you know of any disks that 'start from the middle'? I usually
> > recommend that people place their swap and /var partitions near the
> > beginning of the disk, (for a _slight_ improvement), but maybe there
> > is a good reason not to do this for some disks?
>
> I generally put swap in the middle of the disk, not on the
> "fastest" end. The "fast" end is faster for large transfers,
> but that isn't what swap is about.

Well, I was thinking of machines that are really starved of physical
RAM, 32 MB or less, even down to 4 MB. I generally run swapless on
'real' machines :-).

Also, the higher capcity tracks mean less seeks, so the chance of not
having to seek at all increases slightly.

> Swap tends to have lots of small transfers now and then, in between
> other io. So you want a short seek from wherever the
> access arm is to keep latency down, and the middle of the
> disk has short way both from inner and outer tracks.

Yeah, that would probably be a better idea for machines which are only
really hitting swap on occasions, instead of all the time :-).

John.