Re: os x newbie: partitioning?

In article <C120A2DE.35B95%stimpy1997uk@xxxxxxxxx>, Stimpy
<stimpy1997uk@xxxxxxxxx> wrote:

On 3/9/06 14:00, "Elliott Roper" wrote:

Did you know that OS X will automatically defragment and relocate any
file of more than 8 fragments and less than 20 MB on open?

So, what does it do with fragmented files of greater than 20mb? Do they
ever get defragmented?

As far as I can find out. No, not automatically. I guess the hit on
open is too great, and the benefit too small. A really large file
(greater than a whole cylinder) will incur head seeks whether it is
contiguous or not. It will take a longish time to read into memory
anyway (transfer rate) and I'd bet that in a reasonably large number of
cases (e.g. video clips, it was originally written in huge contiguous
increments, and if it were that ginormous, there won't be enough
contiguous free space to improve its fragmentation anyway. Finally,
since a fairly small number of enormous files will fill a disk, when
one is deleted, it would create wide vistas of contiguous free space
automatically. So, all things considered, there is not much to be
gained by attempting to defrag a disk-full of large files in place.

In the old days in VMS, if things became horribly wedged on disk, I'd
backup a whole disk to tape, ini the disk, then restore from tape. That
was almost always far faster than an in-place defrag, and would do a
far better job. (an hour or so, compared to overnight)

In OS X, I have never defragged a disk with an in-place defragger. I
have on rare occasions ini'd a partition that once contained video
clips, but now I just don't bother. I have never seen any improvement
over simply cleaning the files out in the finder all at once.

I'd say that if one was to change the role of a disk from storing
zillions of little files to being a media scratch, there would be merit
in a once off ini.

--
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