Mail Dovecot - dovecot-uidlist.tmp failed: No space left on device

[soulshepard]

We have a server that has a few big and small imap mailboxes and on all mailboxes randomly we notice this in the logs

Feb 10 14:31:57 servername dovecot[797]: imap([email protected]): Error: write(/home/userx/imap/domainy/info/Maildir/dovecot-uidlist.tmp) failed: No space left on device

but the disk nor the tmp ran out of disk space.. also the inode count has enough room.

when we remove the imap/*/*/Maildir/dovecot* then it suddenly works again?!
the file is not there and there is enough diskspace and inode space.
could it be that there are too many files open etcetc? or multiple users locking the same mailbox?
if it are open file things then i would expdect open file errors.
also there are no quoatas in place..
anyone an idea?

i have read somewhere to set ulimit -HSn 1536 (or higher) in the dovecot config..

 

[soulshepard]

also i notice exim is also reporting. so somehow while there is enought diskspace and inodes suddenly the server reports no space left on device.. very strange.. also not for all people only a few processes.

 

[scsi]

What is the output of:

df -h