Thank you for reply.
Users can connect to only one server at a time. I move the master server to another hardware and at this time it is necessary for users to use the mail.
If this is not a secure configuration, then can I just run "sync_client -A" from the master server, and then switch users to a replica?
After that, swap the roles of master-replica between the servers? I'm right ?
>We use cyrus aggregator aka cyrus murder, and AFAIK fastmail also uses
>multiple
>instances on one server with nginx frontends
Can you give an example of the configuration?
Best regards.
Четверг, 13 сентября 2018, 13:22 +05:00 от Michael Menge <michael.menge@xxxxxxxxxxxxxxxxxxxx>:
Hi,
This setup is NOT SUPPORTED and WILL BREAK if the replication process
is triggered
from the wrong server (user is active on both servers, user switched
from one server
to the other while the sync-log file is still processed, after split
brain) and
some mailboxes have been subscribed, renamed created deleted.....
Also there is the risk of a race condition with subscriptions, if a
user subscribes
to multiple folders, the first will trigger a sync from A to B, but as
the folder
is subscribed on B it will trigger a sync from B to A, witch can undo the next
folder subscription.
These are only some cases that came to my mind. There will be more
cases and it
will be hard to debug. So DON'T DO IT!
What we do is, that we have distributed our users between multiple
instances, and each server is running one instance as master and one other
as replic. In case of failure or maintenance we stop the master instance, and
promote the corresponding replic and configure them so that they will sync
them back. If the old master is up to date we switch them back.
We use cyrus aggregator aka cyrus murder, and AFAIK fastmail also uses
multiple
instances on one server with nginx frontends
Regards,
Michael
Quoting Evgeniy Kononov via Info-cyrus <info-cyrus@xxxxxxxxxxxxxxxxxxxx>:
> Sorry! Previous message was sent by mistake.
>
> For example, I can configure both servers as follows.
>
> Server A.
> -----------------
> /etc/cyrus.conf
> START {
> ...
> syncclient cmd="sync_client -r"
> ...
> }
> SERVICES {
> ...
> syncserver cmd="sync_server" listen="csync"
> ...
> }
>
> /etc/imapd.conf
> ...
> sync_host: SERVER-B
> sync_authname: admin
> sync_password: password
> sync_log: 1
> sync_repeat_interval: 30
> sync_timeout: 600
> sync_shutdown_file: /var/lib/imap/syncstop And the same on server B.
> -----------------
> /etc/cyrus.conf
> START {
> ...
> syncclient cmd="sync_client -r"
> ...
> }
> SERVICES {
> ...
> syncserver cmd="sync_server" listen="csync"
> ...
> }
>
> /etc/imapd.conf
> ...
> sync_host: SERVER-A
> sync_authname: admin
> sync_password: password
> sync_log: 1
> sync_repeat_interval: 30
> sync_timeout: 600
> sync_shutdown_file: /var/lib/imap/syncstop
> Both server will be as master and as slave in one time.
>
> Will there be any problems with this configuration?
> Thank you. --
> Evgeniy Kononov
--------------------------------------------------------------------------------
M.Menge Tel.: (49) 7071/29-70316
Universität Tübingen Fax.: (49) 7071/29-5912
Zentrum für Datenverarbeitung mail:
michael.menge@xxxxxxxxxxxxxxxxxxxx
Wächterstraße 76
72074 Tübingen
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Evgeniy Kononov
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