cyrus imap slow on Fedora 13&14

[Andre Felipe Machado]

Hello,
We actually used pidstat and iwatch to log disk activity of a given webmail
client  upon our cyrus murder/aggregator.

The access pattern was ...err...  "unwise", when compared with thunderbird, for
example.

The webmail client open account, then opens all folders, then lists all
messages, for all folders, then reads entire content from all of them, one by
one, then javascript order the entire list, then split the list in pages to
render at screen...
It can at least be configured to not read entire content from all of them, only
headers, but still one by one...
All these transactions caused disk writes (a "heavy" fs operation) to cache,
index and header cyrus account files, and webservers and imap frontends load.
When you have MANY msg into an inbox, this could be tragic. When you have many
such simultaneous users, becomes a performance disaster.
I suspect that other webmail clients have similar "unwise" access patterns.

So, one should *aggressively* fine tune filesystem for small files writes/updates.

The webmail clients could be redesigned to use wise imap command patterns. Could
cyrus project publish some hints at site?

Good luck.
Andre Felipe Machado

http://www.techforce.com.br/news/linux_blog/lvm_raid_xfs_ext3_tuning_for_small_files_parallel_i_o_on_debian