On 07/02/13 18:19, Adam Goryachev wrote:

problem. Is there some way to instruct the disk (overnight) to TRIM the
extra blank space, and do whatever it needs to tidy things up? Perhaps
this would help, at least first thing in the morning if it isn't enough
to get through the day. Potentially I could add a 6th SSD, reduce the
partition size across all of them, just so there is more blank space to
get through a full day worth of writes?

I have 6 SSD's in a RAID10, and with 3.7.x (I forget which x - 2 or 3 
from memory) md will pass the TRIM down to the underlying devices (at 
least for RAID10 and from memory 1).

I have a cronjob that runs at midnight :

#!/bin/sh
export TIME="%E real\n%U user\n%S sys\n"
for i in / /home /raid10 ; do
	/usr/bin/time /home/brad/bin/fstrim -v $i
done

Based on the run times, and the bytes trimmed count I suspect it works.
All filesystems are ext4. Two of them are passed through encryption, but 
that passes TRIM down also. I do not have the discard option on any 
mounts (that way lies severe performance issues).

Regards,
Brad