[Users] Zimbra doing similar like Exchange DAG
randy at skywaynetworks.com
Tue Nov 6 18:27:33 CET 2018
It sounds like you are referring to two different configurations: an active/passive mailbox server (mb1 fails over to mb1a), and an active/active mailbox server. For the active/passive mailbox server, assuming that you use the default Zimbra install location of /opt/zimbra, and have /opt mounted from network storage, in this case GlusterFS, that should work, but you should be aware that when the day comes that you need to do a fail-over from mb1 to mb1a (assuming it's an unplanned fail over), what you will end up with is a crash-consistent fail-over. This means that when mb1a mounts the /opt volume & begins attempting to start-up the various Zimbra mailbox services, you will see complaints in the log files, such as /opt/zimbra/log/mysql_errors & /opt/zimbra/log/mailbox.log about a recovery from an unexpected shutdown. This does not always work, and sometimes Zimbra services, particularly the mailboxd service, fails to start because MariaDB cannot recover or there is corrupt data in one or more mailboxes. The likelihood of recovery depends on how busy you rmailbox server is. The more busy it is with disk writes, the more likely it is it may not be able to self-recover from a crash consistent copy of the /opt data on GlusterFS. To recover, you may then find you need to use the procedures outlined here: https://wiki.zimbra.com/wiki/Mysql_Crash_Recovery .
In the current Zimbra 8.8.x version, it does not have a means to run in an active/active configuration out of the box. This is because data on the mailbox server is very stateful, such as the mailbox blobs, the mailbox indexes, the MariaDB database, and the redo log file. This capability is on Zimbra's road map, but the earliest version it is expected to appear is within Zimbra X, which is the next major release of Zimbra. In Zimbra X, it contains an architecture change where all Zimbra services will run as Docker containers, which will be orchestrated using Kubernetes. Zimbra X will only contain a subset of the features of the current Zimbra 8.8.x version, with additional features being added, as demand requires.
But, not all is lost. For much of this year, I've been working periodically on an open source project to add active/active capabilities to the 8.8.x version. In theory, it should also work on earlier 8.x releases too, but I haven't tested it outside of 8.8.x yet. So far, I have an active/active Zimbra cluster working, which uses other open source products to extend the shipping version of Zimbra 8.8.x. It relies on abstracting the storage of the mailbox server data in to Ceph, along with deployment of MariaDB's Galera Cluster. I don't have a web site setup for the project yet, but as it gets closer to a deployable status, I'm giving occasional updates on it on the weekly Zeta Alliance calls, and will likewise post updates to this mailing list too.
Randy Leiker ( randy at skywaynetworks.com )
Skyway Networks, LLC
1.800.538.5334 / 913.663.3900 Ext. 100
----- Original Message -----
From: "Naisiew Yeak" <yeak at md.com.my>
To: "users" <users at lists.zetalliance.org>
Sent: Tuesday, November 6, 2018 4:30:50 AM
Subject: [Users] Zimbra doing similar like Exchange DAG
Does anyone know how Zimbra can compare to Exchange DAG?
I am planning to deploy GlusterFS to replicate my /opt to 3 nodes (one arbiter). Any advice for this kind of setup? I actually do it on the mailstore itself. Basically 3 mailstore servers, mb1, mb1a, mb1b. The mb1 is production and mount the volume to /opt. The mb1a has a copy of data and ready to start up. Finally mb1b as quorum.
I hope to run mb1 and mb1a Active/Active. That mean the mariadb should be active/active on both of them. Current Zimbra is not ready for this right?
I am searching for information what is the direction of the new architecture for new Zimbra. Hope someone can share and let me know. I want to begin deploy such foundation for my Hosted Zimbra service. Also use it as demo platform for customer who is asking about Active/Active mailstore (they literacy bring up DAG to compare).
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