Am Sonntag, 7. Oktober 2012 schrieb Swâmi Petaramesh:

Hi,

I have 4 machines, all converted to BTRFS about 6 months ago, now all
running Ubuntu Quantal with kernel 3.5.0-17

The matter is that all these machines are now getting slower and slower
everyday, every disk access causing the disk to be 100% busy for long
periods, to the point that I'm now seriously considering migrating
everything back to ext4...

From the start BTRFS was "not very fast", still satisfactory, but now
it becomes truly unusable.

On one machine, I know have a typical complete boot time to a usable
GUI that is over 4 minutes, with the HD still very busy for a couple
more minutes afterwards, where it used to be around 35-40 seconds in
ext4 !

Is there anything I could do to speed things back (without losing all
my snapshots or doubling the size of data on disk)...?

As told in my previous post its better to first understand the problem. 
What might help here, additionally to what I suggested already, is some 
output of

vmstat 1

and 

iostat -dx 1 /dev/sda

(or maybe even better 5 or 10 seconds interval)

where /dev/sda is device or better partition where the workload happens.

Also the amount of snapshots in use would be helpful I bet.

Ciao,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7