I/O Errors

[Pascal Mouret]

Hello all,

Since I upgraded Cyrus-imap to v2.2.12, I'm experiencing a lot of I/O 
errors, due to the number of open files. Here is a short exceprt of what 
I can read in imapd.log :
[...]
Nov  8 16:15:53 mailup pop3[281152]: IOERROR: opening 
/var/spool/imap/user/lafitte/cyrus.index: Too many open files
Nov  8 16:15:53 mailup pop3[281152]: Unable to lock maildrop for 
lafitte: System I/O error
[...]
Nov  8 16:41:40 mailup imap[267212]: IOERROR: opening 
/var/spool/imap/user/debast/Trash/cyrus.cache: Too many open files
[...]
Nov  8 16:41:56 mailup imap[267212]: IOERROR: opening 
/var/imap/user/d/debast.seen: Too many open files
Nov  8 16:41:56 mailup imap[267212]: DBERROR: error fetching txn cyrusdb 
error
Nov  8 16:41:56 mailup imap[267212]: Could not open seen state for 
debast (System I/O error)
Nov  8 16:41:56 mailup imap[267212]: IOERROR: creating 
/var/spool/imap/user/debast/cyrus.index.NEW: Too many open files
[...]
Nov  8 16:42:20 mailup imap[267212]: IOERROR: opening 
/var/spool/imap/user/waguet/cyrus.index: Too many open files
[...]

I've got about one such error in every minute, and all goes ok for the 
rest of the time.
I checked about my system settings. It does not seem to be a problem of 
a global max number of open files as no other process reports such 
errors. It appears I may tune a maximum number of open files authorized 
per process, but before tweaking that, which appears uneasy to me, I was 
wondering whether there may be an error in my configuration.
I have got about 1000 concurrent users, on a total of 2000 users. I had 
no such problems before upgrading. I kept the same configuration except 
that I changed from BerkeleyDB to skiplist for all databases (except for 
seendb which still uses "flat")
Has anyone already encountered that ?
Any idea ?
Any hint would be greatly appreciated
Thank you very much in advance

    Pascal Mouret

-- 
Pascal Mouret
DSII - Direction du Système d'Information et de l'Informatique
Université de Provence - 3, place Victor Hugo - 13331 Marseille cedex 3
Tél:  04 91 10 64 02            E-mail: pascal.mouret at up.univ-mrs.fr
Fax: 04 91 08 35 00             ou      pascal.mouret at up.univ-aix.fr
(Ligne d'assistance (interne) : 04 91 10 85 55 / 04 42 95 34 54)