Re: [gentoo-user] ext4 reserved space and defragmentation?

[Dale]

Stroller wrote:
>
> I'm pretty sure that just means that Linux will try to put files in
> contiguous sectors, so they're not fragmented, and that as you run out
> of space it's generally harder to do that.
>
> But I would imagine this is particularly the case with the occasional
> large file on a typical filesystem cluttered with small files - if you
> have a 1TB drive and save 9 100GB movie files on it, the remaining
> free space is going to be contiguous, anyway.
>
> Whilst it would be interesting to do some real world testing on big
> hard drives fulla porn, you can safely set the reserved space to 0%
> and forget about it. That message has been there since ext2 and if you
> streaming suddenly starts to stutter when your filesystem is 99% full,
> well, you were going to add another drive to the array, anyway,
> weren't you? Add it in and expand the filesystem and see if that makes
> any difference.
>
> Interestingly, I've just done an fsck on my ext4 media array and it
> shows as 83.8% non-contiguous. It is 1.4TB with 272G or 19% free. I
> can only assume this is because I also use it for backups, and have a
> couple of directories on there of many much smaller files.
>
> Stroller.
>
>
>

I have a 750Gb drive that I put mostly movies on.  I have NCIS and some 
that I got from youtube of old TV shows plus some regular files like OOo 
docs.  I just ran fragck on that a while ago and got this:

72.499201913381% non contiguous files, 2.38433317962776 average fragments.

I also have my /boot partition which has a few kernels on it and their 
config files.  I get this for that partition:

78.4313725490196% non contiguous files, 4.72549019607843 average fragments.

Both of those have lots of free space still.  About half way on the 
750Gb drive and 75% free space on /boot.  I cleaned it out a while back 
and got rid of some old kernels and configs.

My freshly copied /usr directory comes in as this:

3.52929844927837% non contiguous files, 0.524852607939654 average fragments.

That includes the portage tree by the way.  However, there is not much 
difference when portage is unmounted either.  Again, freshly copied just 
this morning and only synced once so far.

I just freshly transfered my OS from one drive to another.  /boot and 
the data drive was untouched tho.  I don't have a place large enough to 
transfer my data partition.  My question is this, isn't there a point 
where there will be fragmentation no matter what file system you use?  
After all, some files are going to be fragmented because of size and 
some are going to be fragmented because they are edited and such.

By the way, resierfs for everything except /boot and portage which uses 
ext2 and ext3 respectively.

Dale

:-)  :-)