[horde] Sessions, caches and other weird things

[Piotr Legiecki]

Hi

I'd like to configure horde (from Debian/lenny) above those (working) 
default settings. In order to do this I'm trying to figure out what is 
behind those horde settings:
- Custom Session Handler Settings/
$conf[sessionhandler]
default is php file based. It is working fine, but I can't list the user 
sessions. To speed up the horde I'v changed  (in php.ini) the 
session.save_path = /var/lib/php5/tmpfs-sess/ to tmpfs filesystem. It 
does not cost much (memory) but should speed up considerably (I hope). 
But it of course didn't help in sessions listing.

$conf[sessionhandler]
[memcache] Use memcache to cache session information?

I have checked it and to my surprise the sessions started to appear in 
the Admin panel. I was surprised because I did not configured memcache 
at all (just installed it from deb) and there is (in 
$conf[sessionhandler]) another option called 'Memcache only' which 
confused me. Why two options about memcache in this config tab?

So I have setup those two options and wonder if my horde is working 
faster ;-) Horde is used by 5 imap/pop3 servers with about 2000 users. 
But I believe that actually much less users logs to horde.

I hope that this simple optimisation is good enough for my setup but 
still wonder what are SQL based sessions good for? For sure they are not 
faster than fast filesystem (especially in RAM) and much more 
complicated to manage. Only some kind of reporting comes to my mind 
which is impossible with file based sessions.

Regards
Piotr L.