[ale] Ubuntu Linux Defrag EXT4

[Michael B. Trausch]

On Mon, 2010-09-13 at 19:47 -0400, Pat Regan wrote:
> I'm running btrfs on my laptop now.  It is the first time I might have
> any reason to think about fragmentation, since copy-on-write tends to
> promote fragmentation.  Is anyone else playing with btrfs?  I'm only
> running it on an SSD so I don't expect to notice it but I am very
> curious how other people are making out. 

I was using it for awhile, but then I ran into a rather nasty bug that
remained unfixed for some time, and I went back to using ext4.

However, when I was using it, I was taking advantage of the COW
capability of the FS quite a bit.  My daily work was _much_ faster, and
the way that I did things changed quite a lot to take advantage of the
ability to cheaply create snapshots of individual files and modify them
and throw them away if desired.  It is the ultimate filesystem for
managing something like a VM on, particularly if that VM runs Windows,
because you can do all the snapshoting and moving and deleting and
reverting with complete transparency to the VM monitor.  It really is
very nice.

I'm looking forward to going back to trying it again; the bugs that I
ran into before are (so I hear, anyway) completely fixed now, and I
should be able to safely use the filesystem in a multi-device layout as
I was previously.  I'm looking forward to the day that btrfs becomes the
preferred stable filesystem, myself.

I never did get around to trying btrfs' online defragmentation support,
but I suspect that I won't need that in majority of the "normal" use
cases that I have; fragmentation isn't a problem on my own personal
workstations on any other filesystem that I have run on in the past,
despite the number of files (and megabytes/gigabytes contained therein)
that I have growing significantly in the past several years.  The only
real problem that I have with the extX family is that it isn't versatile
enough for me, after having had a taste of btrfs.  ;-)

	--- Mike