Hi, I'm are running a classic Dovecot setup:
About ten thousand connected users
mailbox in Maildir format shared via NFS (NetApp)
Director for POP/IMAP
Delivery via Dovecot LDA
All works fine but sometimes I see a spike on the load of POP/IMAP
servers and high disk usage (close to 100%) on NFS NetApp.
When this happens on NFS stats (of POP/IMAP) I can see an high volume of
"lookup, remove, rename" requests.
Example (avg is during normal load, max is request number during the spike):
Lookup avg 100 max 700
Remove avg 50 max 300
Rename avg 50 max 300
Getattr avg 200 max 250
Total NFS avg 600 max 1800
I think that some users are doing some kinds of "intensive" operations
on their mailbox but what and who?
I am currently using "iotop" to monitor the activity of individual users
but I can't figure out who is causing the high number of I/O requests.
Have you any suggestions?
Thanks
--
Alessio Cecchi
Postmaster @ http://www.qboxmail.it
https://www.linkedin.com/in/alessice
