Re: Maximal Mount Check
On Thu, 4 Mar 1999, E.L. Meijer (Eric) wrote:
> > In a message dated 3/4/99 7:40:39 AM Central Standard Time, tpfeifer@snet.net
> > writes:
> >
> > So, defragging your disk isn't a normal Debian maintenance task? Is this true
> > for all you guys that have been running Debian "forever"?
>
> Yes, defragging your disk is _not_ a normal Debian maintenance task. I
> have been running linux for some 3 three years now (started with
> Slackware) and never defragged a linux disk. The point is that the
> ext2 file system is, unlike fat or vfat, mostly `self-defragmenting'.
Yup. The ext2 filesystem is a *lot* more intelligent about such things
than the FAT filesystem ever could be. For example, typically 5-10% of the
space on a partition is reserved for root-only access. Since the
filesystem can generally count on that space being available, it can
usually prevent fragmentation from arising in the first place.
When you add in Linux's intelligent disk-cacheing (any unused RAM is used
as a disk cache) if there *is* fragmentation, you only notice it once,
when the file is first loaded. After that, it's in RAM.
You can often *hear* the difference between filesystems on a noisy drive.
Whit FAT, when you access a file you get a lot of jumping around the disk.
With ext2, you generally hear something like "tick-tick-buzz" as it hits
the inode table a couple of times and then gets the file more-or-less
continuously.
(Of course, I've got 128MB of RAM now. I can log in, start up X, and
launch several shells before I need to load anything that isn't already in
the cache. It's disconcerting the first few times to do all that in
near-total silence. :-> )
About the only time you get fragmentation is if the filesystem gets
*really* full. If it happens, the defrag tools are available, but the best
thing to do is just back up the partition, reformat, and restore from
backup. This defragmentats at least as effectively, and you should really
back stuff up *anyway* before you defrag, right?
Sincerely,
Ray Ingles (248) 377-7735 ray.ingles@fanucrobotics.com
"Engineering is like having an 8 a.m. class and a late afternoon lab
every day for the rest of your life." - Anonymous
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