Il 05.12.2015 10:42 Filip Pytloun ha scritto:
Hello,
I have recently setup mailserver solution using 2-node master-master
setup (mainly based on MySQL M-M replication and GlusterFS with 2
replica volume) on Ubuntu 14.04 (Dovecot 2.2.9).
Unfortunately even with shared-storage-aware setting:
mail_nfs_index = yes
mail_nfs_storage = yes
mail_fsync = always
mmap_disable = yes
With only these setting you don't solve the problem of shared storage.
..I have hit strange issues pretty soon especially when user was
manipulating same mailbox from multiple devices at the same time.
Most issues was about corrupted indexes which was solved easily by just
putting them on local storage of each node:
mail_location =
maildir:/srv/mail/%d/%u:INDEX=/var/lib/dovecot/index/%d/%u
But I still hit issues like this one:
dovecot: lmtp(6276, u...@example.com): Error: Broken file
/srv/mail/example.com/u...@example.com/dovecot-uidlist line 8529: UIDs
not ordered (8527 >= 8527)
Which I am not sure how serious it is or if it's possible to solve or
workaround?
You need Director for POP/IMAP and also LMTP so you can solve all
"Broken file" and "corrupted indexes" problems.
Anyway because of the above and high possibility of GlusterFS
split-brains, I have decided to setup Dovecot Director according to the
docs [1] but I have a couple of questions:
- is custom monitoring still required? Poolmon [2] is 4 year old so I
would suppose there's some progress since that?
For me poolmon works fine.
- it's not possible to have same backends and directors in Dovecot
<2.2.17. I can backport newer Dovecot for Ubuntu Trusty, so this is
not an issue, but..
Yes is possibile (also with < 2.2.17), create two instances, like
dovecot and director, two config directory /etc/dovecot/ and
/etc/director/ and bind on differents IPs.
- documentation states that it still doesn't work for LMTP [3]?
Which is probably important for my setup, because both Postfix
servers
are using dovecot-lmtp for mail delivery so there can be still some
issues (but probably less frequent?) when both servers will deliver
new mails for one user at once.
So do I really have to split directors from backends?
I'm running Director and backend on the same server for POP/IMAP, and in
another configuration and Director for LMTP is on the same server (but
with 2.2.19).
Anyone has experience with clustered Dovecot setup?
Why is Dovecot behaving so bad when it pretends to be shared storage
friendly? Are these issues only specific for older Dovecot?
Or is there something wrong in my architecture design?
You need Director, Dovecot has not problems with shared storage, big
installation are always using shared storage (like NFS).
--
Alessio Cecchi
Postmaster AT http://www.qboxmail.it
http://www.linkedin.com/in/alessice
