Re: Dovecot Replication Errors (only) when using tcps: as the mail_replica Protocol

Am 19.11.20 um 09:30 schrieb James Pattinson:

On 18/11/2020 19:37, Aakash Patel wrote:

...

Hello,

I have two mail servers and am also experiencing sporadic replication errors over tcps, similar to Reuben. Each server is running Dovecot 2.3.11.3 (502c39af9) on Debian 10.6.

*Log entries from MX1* Nov 18 00:39:26 mx1 dovecot: dsync-local(user@example.com): Error: dsync(mx2.example.com): I/O has stalled, no activity for 600 seconds (last sent=mailbox, last recv=mailbox_state) Nov 18 00:39:26 mx1 dovecot: dsync-local(user@example.com): Error: Timeout during state=sync_mails (send=mailbox recv=mailbox) Nov 18 06:39:32 mx1 dovecot: dsync-local(user@example.com)<6bScGpwFtV+vEQAAPHKnuQ>: Error: dsync(mx2.example.com): I/O has stalled, no activity for 600 seconds (last sent=mailbox, last recv=mailbox_state) Nov 18 06:39:32 mx1 dovecot: dsync-local(user@example.com)<6bScGpwFtV+vEQAAPHKnuQ>: Error: Timeout during state=sync_mails (send=mailbox recv=mailbox) *End*

*Log entries from MX2* Nov 18 00:29:55 mx2 dovecot: dsync-local(user@example.com)<fKK3JzWxtF9zAgAA5XpYKg>: Error: Couldn't lock /var/vmail/user@example.com/.dovecot-sync.lock: fcntl(/var/vmail/user@example.com/.dovecot-sync.lock, write-lock, F_SETLKW) locking failed: Timed out after 30 seconds (WRITE lock held by pid 628) Nov 18 00:34:56 mx2 dovecot: dsync-local(user@example.com)<9IKaB2KytF92AgAA5XpYKg>: Error: Couldn't lock /var/vmail/user@example.com/.dovecot-sync.lock: fcntl(/var/vmail/user@example.com/.dovecot-sync.lock, write-lock, F_SETLKW) locking failed: Timed out after 30 seconds (WRITE lock held by pid 628) Nov 18 00:39:26 mx2 dovecot: doveadm: Error: dsync(mx1.example.com): I/O has stalled, no activity for 600 seconds (last sent=mail_change (EOL), last recv=mailbox) Nov 18 06:39:32 mx2 dovecot: doveadm: Error: dsync(mx1.example.com): I/O has stalled, no activity for 600 seconds (last sent=mail_change (EOL), last recv=mailbox) *End*

I have configured "replication_full_sync_interval = 1 hours", which explains why some of the sync errors occur at the same increment on the hour (if the error does occur).

I've tested replication over tcps using either IPv6 or IPv4 -- this did not appear to make a difference.

Changing replication to occur over tcp solves the issue (with "ssl = yes" commented out, as well).

IMAP clients are primarily connecting to MX1 using SSL, which works well (SSL connections to MX2 also work). These are very low traffic machines at the moment (just 1 user as I continue testing).

I've attached the output of "dovecot -n" from each server.

Are there known bugs with replication using SSL? I'd appreciate any guidance.

Thank you, AP

For what it's worth, I had the same issue when setting this up a few weeks ago. I switched to using SSH based transport and it's been great ever since. Is that an option for you?

dsync_remote_cmd = ssh -l%{login} %{host} doveadm dsync-server -u%u mail_replica = remote:root@xx.xx.xx.xx

Cheers James

I am seeing the same errors with tcps. For me with version 2.3.11.3 under CentOS. An attempt without SSL looks better, I will probably also try it via ssh.

Best regards Philipp