Re: Migrating, syncing, maybe load-balancing/failover two dovecot servers?

ok just a few quick things about replication

1. you should upgrade both versions to at least dovecot-2.3.19.1.tar.gz (2.3.18 had issues on larges folder counts - you will probably run into this on smaller servers but just sharing the experience)

2. i found replication worked better without using ssl

3. i went through the sync failures etc as well and found that NOT using NFS etc is the way to go

4. I can provide (or if you look on the mailing lists) my config for SCOM - it took a month of tweeking but finally got a good config that worked.

5. One thing i just remembered that you really should run a pgsql database for user auth, this way the two system will stay up to date automatically everytime an email box is modified. The replicator service selects users from a database to keep the mbox's in sync automatically

the above are the basics but i find dovecot runs extremely well vs cyrus that i was running previous

Good job to the designers !

Happy Wednesday !!! Thanks - paul

Paul Kudla

Scom.ca Internet Services http://www.scom.ca 004-1009 Byron Street South Whitby, Ontario - Canada L1N 4S3

Toronto 416.642.7266 Main 1.866.411.7266 Fax 1.888.892.7266 Email paul@scom.ca

On 1/4/2023 4:24 PM, Gerben Wierda wrote:

So, I did set it up.

As I am using not real users (but a cram md5 passwd db file with every user uid=dovecot, gid=mail) and my dovecots are owning everything in the mail store I had to synchronise uid/gid of the dovecots on both ends

After I did that, I tested the sync. And while it has worked (I now have an equal sized store at both ends), one side (running 2.3.17, the sending 'old server') was throwing up quite a bit of this:

Jan 04 20:13:15 doveadm(74435): Error: write(<local>) failed: Timed out after 60 seconds Jan 04 20:13:15 doveadm(74435): Panic: file ioloop.c: line 865 (io_loop_destroy): assertion failed: (ioloop == current_ioloop) Jan 04 20:13:15 doveadm(74435): Error: Raw backtrace: 0
libdovecot.0.dylib                  0x000000010db6d157 backtrace_append libdovecot.0.dylib                  0x000000010db7973b

• 58 -> 1   libdovecot.0.dylib                  0x000000010db6d255 backtrace_get + 31 -> 2   libdovecot.0.dylib
  0x000000010db79ff3 default_fatal_finish + 60 -> 3   libdovecot.0.dylib
  0x000000010db78afa default_error_handler + 0 -> 4

i_internal_error_handler + 0 -> 5   libdovecot.0.dylib
0x000000010db78c Jan 04 20:13:15 doveadm(74435): Error: b8 i_fatal + 0 -> 6
libdovecot.0.dylib                  0x000000010db8fa1f io_loop_destroy + 826 -> 7   doveadm-server                      0x000000010d3445fc doveadm_print_server_flush + 254 -> 8   doveadm-server
0x000000010d33df1e doveadm_print + 44 -> 9   doveadm-server
0x000000010d32bd5b cmd_dsync_run + 1618 -> 10
doveadm-server                      0x000000010d32db67 doveadm_mail_next_user + 479 -> 11  doveadm-server
0x000000010 Jan 04 20:13:15 doveadm(74435): Error: d32e8bb doveadm_cmd_ver2_to_mail_cmd_wrapper + 2439 -> 12  doveadm-server
0x000000010d33dc0c doveadm_cmd_run_ver2 + 1083 -> 13
doveadm-server                      0x000000010d34224a client_connection_tcp_input + 1579 -> 14  libdovecot.0.dylib
0x000000010db8efe1 io_loop_call_io + 114 -> 15
libdovecot.0.dylib                  0x000000010db910cf io_loop_handler_run_internal + 314 -> 16  libdovecot.0.dylib
0x000000010db8f3fb io_loop_handler_run + Jan 04 20:13:15 doveadm(74435): Error:  212 -> 17  libdovecot.0.dylib
0x000000010db8f2e6 io_loop_run + 81 -> 18
libdovecot.0.dylib                  0x000000010db075e0 master_service_run + 24 -> 19  doveadm-server
0x000000010d344c3f main + 292 -> 20  dyld
0x000000011c73952e start + 462 Jan 04 20:13:15 doveadm(74435): Fatal: master: service(doveadm): child 74435 killed with signal 6 (core dumps disabled - https://dovecot.org/bugreport.html#coredumps https://dovecot.org/bugreport.html#coredumps) Jan 04 20:16:05 lmtp(pid 74518 user gerben): Warning: replication(gerben): Sync failure: Timeout in 2 secs Jan 04 20:17:05 doveadm(74522): Error: write(<local>) failed: Timed out after 60 seconds Jan 04 20:17:05 doveadm(74522): Panic: file ioloop.c: line 865 (io_loop_destroy): assertion failed: (ioloop == current_ioloop) Jan 04 20:17:05 doveadm(74522): Error: Raw backtrace: 0
libdovecot.0.dylib                  0x00000001050d3157 backtrace_append libdovecot.0.dylib                  0x00000001050df73b

• 58 -> 1   libdovecot.0.dylib                  0x00000001050d3255 backtrace_get + 31 -> 2   libdovecot.0.dylib
  0x00000001050dfff3 default_fatal_finish + 60 -> 3   libdovecot.0.dylib
  0x00000001050deafa default_error_handler + 0 -> 4

i_internal_error_handler + 0 -> 5   libdovecot.0.dylib
0x00000001050dec Jan 04 20:17:05 doveadm(74522): Error: b8 i_fatal + 0 -> 6
libdovecot.0.dylib                  0x00000001050f5a1f io_loop_destroy + 826 -> 7   doveadm-server                      0x00000001048aa5fc doveadm_print_server_flush + 254 -> 8   doveadm-server
0x00000001048a3f1e doveadm_print + 44 -> 9   doveadm-server
0x0000000104891d5b cmd_dsync_run + 1618 -> 10
doveadm-server                      0x0000000104893b67 doveadm_mail_next_user + 479 -> 11  doveadm-server
0x000000010 Jan 04 20:17:05 doveadm(74522): Error: 48948bb doveadm_cmd_ver2_to_mail_cmd_wrapper + 2439 -> 12  doveadm-server
0x00000001048a3c0c doveadm_cmd_run_ver2 + 1083 -> 13
doveadm-server                      0x00000001048a824a client_connection_tcp_input + 1579 -> 14  libdovecot.0.dylib
0x00000001050f4fe1 io_loop_call_io + 114 -> 15
libdovecot.0.dylib                  0x00000001050f70cf io_loop_handler_run_internal + 314 -> 16  libdovecot.0.dylib
0x00000001050f53fb io_loop_handler_run + Jan 04 20:17:05 doveadm(74522): Error:  212 -> 17  libdovecot.0.dylib
0x00000001050f52e6 io_loop_run + 81 -> 18
libdovecot.0.dylib                  0x000000010506d5e0 master_service_run + 24 -> 19  doveadm-server
0x00000001048aac3f main + 292 -> 20  dyld
0x000000011487652e start + 462 Jan 04 20:17:05 doveadm(74522): Fatal: master: service(doveadm): child 74522 killed with signal 6 (core dumps disabled - https://dovecot.org/bugreport.html#coredumps https://dovecot.org/bugreport.html#coredumps)

Turns out, this is a known (and pretty old) problem (https://www.mail-archive.com/dovecot%40dovecot.org/msg85388.html https://www.mail-archive.com/dovecot%40dovecot.org/msg85388.html) and my dovecot on the old server (macOS + MacPorts) is newer than the dovecot on the new one. I should go back to a 2.3.16 on the old server.

It seems the syncing works (or has worked) nonetheless, but it doesn't feel good.

Gerben Wierda (LinkedIn https://www.linkedin.com/in/gerbenwierda) R&A IT Strategy https://ea.rna.nl/ (main site) Book: Chess and the Art of Enterprise Architecture https://ea.rna.nl/the-book/ Book: Mastering ArchiMate https://ea.rna.nl/the-book-edition-iii/

...

On 4 Jan 2023, at 13:54, Paul Kudla mailto:paul@scom.ca> wrote:

maybe look a replicator / replication

its designed to do exactly that

Happy Wednesday !!! Thanks - paul

Paul Kudla

Scom.ca http://Scom.ca Internet Services <http://www.scom.ca http://www.scom.ca> 004-1009 Byron Street South Whitby, Ontario - Canada L1N 4S3

Toronto 416.642.7266 Main 1.866.411.7266 Fax 1.888.892.7266 Email paul@scom.ca mailto:paul@scom.ca

On 1/4/2023 7:46 AM, Gerben Wierda wrote:

...

I am in the process of migrating from dovecot on one OS (macOS/darwin) to a new server running dovecot with another OS (Ubuntu Linux 22.4). I have mostly copied/adapted the setup of the old server to the new. I am in the process of finishing that and adding some stuff that still needs to be added/migrated, like rspamd. And the data of course before the new one takes over from the old. I have done a migration before (MacOS X Server dovecot to MacPorts dovecot on macOS), many years ago, I recall that I used dovecot syncing but also rsync and I don't really recall (and anyway, the software has changed since) I have been thinking about keeping them both alive, with one as a failover for the other. They will not share their storage (e.g. NFS), So, I was wondering if I can do something with syncing between instances and dovecot director. I have been looking at the documentation, but a quick scan reveals I cannot locate some sort of tutorial and I am uncertain what will work and what not. If keeping both alive in parallel is too problematic, it is OK to have regular syncing in one direction (old to new) at first and then switch over and have syncing in the other direction (new to old) Can someone enlighten me? Gerben Wierda (LinkedIn https://www.linkedin.com/in/gerbenwierda) R&A IT Strategy https://ea.rna.nl/ (main site) Book: Chess and the Art of Enterprise Architecture https://ea.rna.nl/the-book/ Book: Mastering ArchiMate https://ea.rna.nl/the-book-edition-iii/

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