defrag

[Jerry McAllister]

On Fri, Mar 02, 2007 at 02:17:31AM +0100, Ivan Voras wrote:

> Jerry McAllister wrote:
> 
> > Well, it would do some, but for the greatest effect, you would need:
> >   dump + rm -rf * + restore
> 
> This is nitpicking so ignore it: deleting all files on UFS2 volume won't
> restore it to it's pristine state because inodes are lazily initialized.
> It doesn't have anything to do with fragmentation, but will make fsck
> run a little longer.
> 

True it wouldn't be quite pristine because files would have different
inodes assigned when they get reloaded than they might have if it was
newfs-ed before reloading.   That might make fsck run a tiny bit slower.
But it wouldn't be any difference for a running system file access.

On the other hand, doing all this either way wouldn't make any difference 
in performance for file access in a running system because so-called
fragmentation is not an issue in the UNIX file system - except in
the small possibility that it might make a bit of difference in a
file system filled to capacity, well in to the reserve where non-root
processes are not allowed to write anyway.   I don't know just how 
close to absolutely full you have to get to see any difference, but it
is beyond what users would normally get to.

////jerry