how to fix this warnig

[Chandran Manikandan]

Hi Friends,

I have noticed below log in dovecot.log on my machine Centos 6.7 32 bit.

 Warning: Inotify instance limit for user 89 (UID vpopmail) exceeded,
disabling. Increase /proc/sys/fs/inotify/max_user_instances

I have increased manually but after reboot goto the same existing default
value.
How do i fix this issue permanently.

Advance thanks for your help.

-- 
*Thanks,*
*Manikandan.C*
*System Administrator*