Moving messages on test server, dovecot.index.log was locked for x seconds on cephfs

I am getting on a test environment were no users are logging in a dovecot.index.log was locked when moving messages with doveadm move -u testuser Archive/2012 mailbox INBOX/inbox BEFORE 2013-01-01.

doveadm(testuser): Warning: Transaction log file /var/dovecot/testuser/index/.INBOX.inbox/dovecot.index.log was locked for 215 seconds (rotating while syncing)

I have read about how this can be related to default locking fcntl and nfs, anyone having this solved with cephfs? https://www.dovecot.org/list/dovecot/2009-January/036194.html