Hi,

try to start dovecot with "ulimits -u 10240 -n 40000" and increase the value in /proc/sys/fs/inotify/max_user_instances around to 1024.

I also suggest to use XFS instead of ext4, for example after a crash XFS is immediately available.

Ciao

Il 05/11/2014 16:07, absolutely_free@libero.it ha scritto:

Hi, Since few days I noticed very high load on my mailserver (Centos 6.6 64bit, 8 GB RAM, 2 x CPU 3.00GHz I am using Dovecot + Postfix + Roundcube + Nginx.

I have about 10000 users. Spool is on network attached storage (Coraid).

File system is ext4 (mounted with noatime).

Problem appears almost every morning (while load is normal during afternoon).

I suspect that this can be related to some user that have so many messages in his mailbox. How can I troubleshoot this?

Here some messages that I got in maillog:

Warning: Maildir: Scanning /var/spool/pop/domains/xxxx.it/YYYYYYYYY/Maildir/new took 71 seconds (1 readdir()s, 1 rename()s to cur/)

Warning: Maildir /var/spool/pop/domains/zzzz/WWWWWWWWWWWW/Maildir/.Trash: Synchronization took 74 seconds (5 new msgs, 0 flag change attempts, 0 expunge attempts)

dovecot: imap(xxxx@zzzz.it): Warning: Inotify instance limit for user 89 (UID postfix) exceeded, disabling. Increase /proc/sys/fs/inotify/max_user_instances

tail: inotify cannot be used, reverting to polling: Too many open files

My relevant dovecot conf:

mail_location = maildir:/coraid-s2l2/domains namespace { type = private separator = . prefix = INBOX. inbox = yes } mail_uid = 89 mail_gid = 89 mail_fsync = never first_valid_uid = 89 first_valid_gid = 89 maildir_very_dirty_syncs = yes mbox_write_locks = fcntl

thank you very much!