Over many months I've been getting frequent errors in synchronization using dsync. They are hard to reproduce, and aren't always of the same nature, but there's a particular case that I can reproduce 100% of the time. It involves read status being synced in the wrong direction when two machines are both synchronizing with a server.
I'm reposting below a message that gives the method for reproducing the problem. I can still reproduce it with Ubuntu's 2:2.3.7.2-1~bionic packages. I also have problems with only one machine synchronizing with a server, but those I can't reproduce on demand. I'm happy to try patches or test other things. I'm using Maildir storage. Thanks for any suggestions! Dan On Feb 16, 2019, Dan Christensen via dovecot <dovecot@dovecot.org> wrote: > I'm running dovecot 2.3.4.1 from https://repo.dovecot.org/ on Ubuntu > 18.04 on three machines that I'll call server, laptop1 and laptop2. > > Both laptop1 and laptop2 run dovecot sync against server to keep local > copies of my imap folders. Even when I initially had only two machines, > laptop1 and server, I occasionally noticed that flags were lost, usually > custom flags used by Gnus, but I couldn't reliably reproduce the > problem. > > Now that I have two laptops syncing against the server, the problem has > gotten worse and I figured out a way to reproduce it: > > - on server: create new IMAP folder test, and put two read messages in it > - on laptop1: doveadm sync -u user -l 10 -m test -f user@server > - on laptop2: doveadm sync -u user -l 10 -m test -f user@server > > At this point, all three machines show the two messages M1 and M2 > as being read. > > - on laptop1: mark message M1 unread > - on laptop2: mark message M2 unread > - on laptop1: doveadm sync -u user -l 10 -m test -f user@server > Both laptop1 and server have M1 unread, M2 read, as expected. > - on laptop2: doveadm sync -u user -l 10 -m test -f user@server > Now laptop2 and server have M1 *read*, M2 unread. > - on laptop1: doveadm sync -u user -l 10 -m test -f user@server > Now laptop1 and the server have both M1 and M2 *read*. > - on laptop2: doveadm sync -u user -l 10 -m test -f user@server > Now laptop2 has both read as well. > > The two lines that say "*read*" are wrong in my opinion. dsync > propagated a read mark to an unread message, even though that message > was marked unread more recently than it was marked read. > > I usually use stateful sync, and get many related problems. > I just did a test in which M1 and M2 started out read, and I > started with empty files named dstate.test on laptop1 and laptop2. > Then I did the above procedure, using the command > > doveadm sync -u user -l 10 -m test -s "`cat dstate.test`" user@server > > dstate.test > > At the end, laptop2 and server had both messages unread (which is good), > but laptop1 had only M1 unread, and repeated runs of the sync command > did not correct this. So the stateful sync failed to detect a change. > > Are these bugs in dovecot? Is there more information that I can > provide? The output of doveconf -n on one machine is below, and > the others are almost identical. > > Thanks for any help! > > Dan > > # 2.3.4.1 (3c0b8769e): /etc/dovecot/dovecot.conf > # OS: Linux 4.15.0-45-generic x86_64 Ubuntu 18.04.1 LTS > # Hostname: laptop2 > auth_mechanisms = plain login > listen = 127.0.0.1 > mail_index_log2_max_age = 10 days > mail_index_log_rotate_min_age = 1 days > mail_index_log_rotate_min_size = 300 k > mail_location = maildir:~/Maildir > 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 { > args = scheme=CRYPT username_format=%u /etc/dovecot/users > driver = passwd-file > } > protocols = imap > service imap-login { > inet_listener imap { > address = * > port = 143 > } > inet_listener imaps { > address = * > port = 943 > ssl = yes > } > } > service imap { > process_limit = 25 > } > ssl_cert = </etc/dovecot/private/dovecot.pem > ssl_client_ca_dir = /etc/ssl/certs > ssl_dh = # hidden, use -P to show it > ssl_key = # hidden, use -P to show it > userdb { > args = username_format=%u /etc/dovecot/users > driver = passwd-file > } > protocol lda { > postmaster_address = [elided] > } > protocol imap { > mail_max_userip_connections = 20 > }
