Disaster Recovery

In this article we’ve seen some disaster scenarios that can occur and some traditional disaster recovery solutions, as well as an overview of Zextras solution.

With the following article, however, we want to go over how Disaster Recovery solution works with the help of Zextras Backup and why it is actually efficient.

How to Recover after a Disaster

So the disaster happens, although you were sure you had taken every precaution. And I’m not only talking about natural disaster, but just thinking about, for example, hardware failure of a vital filesystem (or more than one) or of the physical machine hosting Zimbra, or contents of a vital filesystem made unusable by different kind of factors (both internal or external), or critical failure of software or OS.

Well, not all is lost. We can proceed to service recovery with the help of Zextras Backup.

How can Zextras Backup Help?

With Zextras Backup we can easy and safely perform the second recovery step, using the Import Backup feature. It allows you to restore a basic Zimbra installation to the last valid time from your old server, simply using its backup path as the import one. But this is just a possible scenario.

Let’s see now how the recovery process works:

After installing and configuring Zimbra on a new server, install Zextras Suite. After completing those steps, mount the backup folder from the old server to the new one. Now start the External Restore on the new server using the following command:

zxsuite backup doExternalRestore /path/to/the/old/store

This operation will immediately, as a first step, create domains, accounts and distribution lists, so the system will be ready for your users. After this one, a second step will restore Emails and other mailbox items.

If your backup is on a third party storage, then you need to proceed as follows:

If the backup was on S3, create a new bucket configuration with the same settings as the old one, without configuring it as the BLOB store. Otherwise mount the remote folder. Then retrieve the metadata using the following command:

zxsuite backup retrieveMetadataFromArchive {source} {destination}

After doing that use the blobArchive option when running the External Restore to make sure that the operation will retrieve the BLOBs from the old backup.

If the backup folder from the old server is not available, well … you could still use an older copy of the backup folder, if you have one. (of course only old items will be restored)

Configurations

Please note that although Server and Global settings are backed up, they are not automatically restored.

Zextras Backup, thanks to its high-level integration with Zimbra, allows you to restore your data also on a server with a different environment, such as different OS or Zimbra Release from the old one. You need nothing but the minimum Zimbra version required to run Zextras Suite.

A very convenient CLI command, comes with Zextras Backup to help you either you want to create a perfect copy of the old server or take its settings to adapt them to a new environment. That is getServerConfig.

To learn more about how this command works, we suggest you read our documentation.

Disaster Recovery with VMs and Snapshots

Thanks to the advent of highly evolved virtualization solutions in the past years, virtual machines are now the most common way to deploy server solutions such as Zimbra Collaboration Suite. In case of a disaster, it’s always possible to roll back to the latest snapshot and import the missing data using Zextras Backup External Restore feature, using the server’s backup path as the import path.

Please note that when you are using these kinds of systems, it’s crucial to be sure that the Backup Path isn’t either part of the snapshot or altered in any way when rolling back in order for the missing data to be available for import.

You can also perform a disaster recovery from a previous VM State. In order to do that with Zextras Backup, you need to proceed as follows:

First of all you have to restore the last valid backup into a different VM in an isolated network, being sure that users can’t access it and there is no active mail traffic. Then, after switching on the clone and waiting for Zimbra to start, disable Zextras Backup’s RealTime Scanner.

Now connect the virtual disk containing the untainted backup path to the clone and mount it (of course on a different path). At this point you can start an External Restore using the Backup Path as the Import one.

By doing this, all items in the backup path will be analyzed and the missing ones imported. This will speed up disaster recovery. You can repeat these steps as many times as necessary.

Suggestions

Since, as we have described in this article, prevention is better than cure, here are some small tips to reduce the chances of disaster:

  • Always keep critical file systems on different drives
  • Use a monitoring tool for your server so that you are alerted in time of any anomalies or errors as soon as they occur
  • Carefully plan updates and migrations

Technical writer at Zextras. Linux and technology enthusiast. He describes himself as an atypical and polyhedric IT expert, thanks to a creative and open minded attitude, and to the experience gained over time as an IT technician, system engineer and developer.

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