Hello.

Dovecot version: 2.2.36
OS: CentOS Linux release 7.9.2009 (Core)
Kernel: 3.10.0-1160.11.1.el7.x86_64

I have two dovecot servers in replication master/master. Sometimes happens that deliver or imap process hangs and causing high CPU usage.
In log's I only see locking failures but not initial cause why this happened.
For mail storage I use ZFS pool with compression enabled.

I made some digging and find this option: mmap_disable = yes. I will try this setting today evening.

But I wondering if you have any idea why this happening and how to start solving this problems? Is there any additional setting like mmap_disable that can help solved this issues?