Poor Roundcube performance with default configuration

[Alexander Haensch]

In my experience the problem with Ext2/3/4 and synchronous file
operation leads to a writeout of all not yet synced inodes on the
filesystem. This process is slow if you have mysql and others working on
the same ext partition.
The only solution is to partition your disk beforehand or use a
different filesystem like btrfs.
There is a tool to migrate ext to btrfs [1], it worked fine for me. The
overall stability of btrfs is maybe not as high as ext4 : coreOS migrate
to ext4 [2].
>From my small server experience, i would recommend a migration to btrfs,
if your server is already running and you have a recent kernel, i use
3.18 at the moment on my server.
The performance on a single btrfs partition is much better than with ext4.

If you have the possibility, you should partition multiple ext4 or even
Xfs partitions and use them in a mdraid for data redundancy.
If you care about your data, i would not recommend to play with the sync
options too much. If you have a battery backed server you are save if
there is a power outage, but in the case of a server crash you
definitivly lose data. In my optinion you should optimize your
filesystem first and if you still need more performance, look to SSD or
even RAM cache.

Alexander


[1] https://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3
[2] https://lwn.net/Articles/627232/