Mail replication does not work

[Pavel Just]

Hi,

I have installed two Debian 10.5 (SSH server) systems
and I would like replicate mails between them.
But the replication is very unstable.
Before start of dovecot
Source mailbox: 278 messages, Destination mailbox: 0 messages
Another mailbox: 16887 messages, D.. 0 messages
After start of dovecot
Source mailbox: 278 messages, Destination mailbox: 303 messages
Another mailbox: 16887 messages, Dest..: 31904 messages
In many cases replication hangs.
Error message is in the end of the message.
If replication hangs, after restart a lot of mail are copied
from destination back to source and mailbox grows without new messages.
Postfix was stopped during replication.

Please, what is wrong in my configuration (except security :-) ?

--
Pavel


# 2.3.11.3 (502c39af9): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.11 (6c69c917)
# OS: Linux 4.19.0-10-amd64 x86_64 Debian 10.5 
# Hostname: mail.simac.cz
disable_plaintext_auth = no
doveadm_password = # hidden, use -P to show it
first_valid_uid = 1001
last_valid_uid = 32000
mail_location = mbox:~/mail:INBOX=/var/mail/%u
mail_plugins = " notify replication"
mail_privileged_group = mail
mail_temp_dir = /var/tmp
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext
namespace inbox {
  inbox = yes
  location = 
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }                                                                                                                                                                                 
  prefix =                                                                                                                                                                          
}                                                                                                                                                                                   
passdb {                                                                                                                                                                            
  driver = pam                                                                                                                                                                      
}                                                                                                                                                                                   
plugin {                                                                                                                                                                            
  mail_replica = tcp:192.168.240.2:12345
  sieve = file:~/sieve;active=~/.dovecot.sieve
}
protocols = " imap sieve pop3"
service aggregator {
  fifo_listener replication-notify-fifo {
    mode = 0666
    user = root
  }
  unix_listener replication-notify {
    mode = 0666
    user = root
  }
}
service doveadm {
  inet_listener {
    port = 12345
    ssl = no
  }
}
service replicator {
  process_min_avail = 1
  unix_listener replicator-doveadm {
    mode = 0666
    user = root
  }
}
service stats {
  unix_listener stats-reader {
    mode = 0666
    user = root
  }
  unix_listener stats-writer {
    mode = 0666
    user = root
  }
}
ssl = no
userdb {
  driver = passwd
}
protocol lmtp {
  mail_plugins = " notify replication sieve"
}
protocol lda {
  mail_plugins = " notify replication sieve"
}
____________________________________ Error message ________________
Sep  2 14:08:00 backup dovecot: doveadm: Panic: file mbox-lock.c: line 796 (mbox_lock): assertion failed: (lock_type == F_RDLCK || mbox->mbox_lock_type != F_RDLCK)
Sep  2 14:08:00 backup dovecot: doveadm: Error: Raw backtrace: /usr/lib/dovecot/libdovecot.so.0(backtrace_append+0x3d) [0x7f300ef00eed] -> /usr/lib/dovecot/libdovecot.so.0(backtrace_get+0x1e) [0x7f300ef0100e] -> /usr/lib/dovecot/libdovecot.so.0(+0xf465b) [0x7f300ef0a65b] -> /usr/lib/dovecot/libdovecot.so.0(+0xf46f1) [0x7f300ef0a6f1] -> /usr/lib/dovecot/libdovecot.so.0(+0x514a6) [0x7f300ee674a6] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0x438e5) [0x7f300f0108e5] -> /usr/lib/dovecot/libdovecot-storage.so.0(mbox_save_begin+0x6fd) [0x7f300f05fa7d] -> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_save_begin+0x92) [0x7f300f0299e2] -> /usr/lib/dovecot/libdovecot-storage.so.0(mail_storage_copy+0x89) [0x7f300f01c4e9] -> /usr/lib/dovecot/modules/lib15_notify_plugin.so(+0x246f) [0x7f300e71846f] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0x5cb3c) [0x7f300f029b3c] -> dovecot/doveadm-server(+0x4f805) [0x556ee519a805] -> dovecot/doveadm-server(+0x501f7) [0x556ee519b1f7] -> dovecot/doveadm-server(dsync_mailbox_import_changes_finish+0x164) [0x556ee519dba4] -> dovecot/doveadm-server(dsync_brain_sync_mails+0x735) [0x556ee5198e85] -> dovecot/doveadm-server(dsync_brain_run+0x218) [0x556ee5194858] -> dovecot/doveadm-server(+0x49eae) [0x556ee5194eae] -> dovecot/doveadm-server(+0x5aa6f) [0x556ee51a5a6f] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x69) [0x7f300ef20989] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0x131) [0x7f300ef21ed1] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0x4c) [0x7f300ef20a2c] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x40) [0x7f300ef20ba0] -> dovecot/doveadm-server(+0x2e20e) [0x556ee517920e] -> dovecot/doveadm-server(+0x2fa56) [0x556ee517aa56] -> dovecot/doveadm-server(+0x45cad) [0x556ee5190cad] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x69) [0x7f300ef20989] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0x131) [0x7f300ef21ed1] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0x4c) [0x7f300ef20a2c] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x40) [0x7f300ef20ba0] -> /usr/lib/dovecot/libdovecot.so.0(master_service_run+0x13) [0x7f300ee9a9c3]
Sep  2 14:08:00 backup dovecot: doveadm: Fatal: master: service(doveadm): child 1977 killed with signal 6 (core dumps disabled - https://dovecot.org/bugreport.html#coredumps)