very slow syncing, any ideas?

[Marten Lehmann]

Hello,

> Looking at taht i'd say you're VERY badly CPU bound.  a simple dd/cp 
> doesn't do anything to the mail but IMAP ops will require some CPU 
> work....Cyrus also will probably be forcing syncs but your I/O load 
> doesn't look that high (my mfe's run more I/O and they're not storing 
> any mail, just logs and temporary files for virus/spam scanning heh, and 
> they only have a little IDE HDD each)

I found the option berkeley_cachesize which is way too low by default. 
Transactions just reading or writing db-entries (i.e. changes of flags) 
are much faster now.

Indead, the imapsync processes are causing much load:

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
20461 root      25   0 79988  36m 2488 R   63  3.6  13:24.10 imapsync
20925 root      25   0 14908 8196 2664 R   57  0.8   0:31.49 imapsync

But what does them make so cpu-expensive?

> I'd guess you're being CPU bound

What would you do if you would need to migrate from Maildir to cyrus? It 
is not important for me to keep the flags. I would be happy if I could 
move all message files to the appropriate cyrus folder. But will cyrus 
detect them automatically? Or is there any rebuild-command required?

Regards
Marten