Submitted by it_onyxar on Tue, 07/23/2013 - 14:54
I would like to have a fail over server in my premise so that when primary is down the secondary server automatically takes the primary server role. Is there any document available for that.
One more thing suppose primary is down the secondary server in action and take the role of primary. Is there any disturbance for my Email users. What about the users that they use pop3 service. Whether they want to download all the old emails again from the secondary?
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Submitted by andreychek on Tue, 07/23/2013 - 21:45 Comment #1
Howdy -- there's a variety of methods for having a backup/failover server.
The simplest, and most common way to do that, would be to have two separate servers -- and each night, generate a set of Virtualmin backups, copy those backups to the failover server, and restore them there. That can all be done via cron.
And then, if your primary server fails, you can manually switch the DNS to use the failover server.
There are more automated ways to handle failover available. The Cloudmin product we offer provides two ways of handling failover.
If you have a SAN or other shared storage available to you, and your Virtualmin servers are VPS's, you could use this failover system here:
https://www.virtualmin.com/documentation/cloudmin/vm/failover
The advantage of it is that when the backup system comes online, it's using the disk image stored on the VPS server, so it would be in the exact state the previous server was in, with all the data that was there.
As soon as the new system can boot, it can be serving requests exactly as the previous server had been.
Alternatively, if you aren't using VPS's and shared storage, Cloudmin can be configured to monitor your primary server, and if it goes down, can switch the DNS records to point to a backup server. That's described here:
https://www.virtualmin.com/documentation/cloudmin/vm/roundrobin
If you use that second system, you could use the following in order to replicate your domains and settings from your primary server to the backup server:
https://www.virtualmin.com/documentation/cloudmin/vm/vsync
You have the option to specify how frequently data is sync'd between the primary and backup servers.
Submitted by it_onyxar on Wed, 07/24/2013 - 00:56 Comment #2
I would like to have two servers. One primary and secondly failover server. Is there any documents available for that?
Submitted by andreychek on Wed, 07/24/2013 - 08:20 Comment #3
Yup, all the methods I described above utilize a primary server, along with a secondary failover server.
I suspect you'd probably either want to use the first method (which is the simplest, but there's no documentation describing it), or the third (last) method I described.
The third method would require the purchase of a Cloudmin license.
In that case, you'd also want to use a third server for installing Cloudmin onto, as it needs to be able to monitor the primary and secondary servers.
The above documentation describes this, but Cloudmin would also need to be hosting your DNS records in order for that to work.
Submitted by it_onyxar on Mon, 07/29/2013 - 14:10 Comment #4
In this situation I dont want to go for Cloudmin. But I need one more failover server if some thing happen to the main primary server automatically the secondary server to be up. Could you please describe the steps to achieve that.
Submitted by andreychek on Mon, 07/29/2013 - 15:25 Comment #5
There's a lot of ways to perform failover outside of Cloudmin. However, those would need to be setup manually using third party technologies, and we don't have instructions for doing that.
What you could do is search on Google for methods of handling failover on Linux, and if you have any questions regarding how Virtualmin fits into that, feel free to let us know.
You could also ask that question on the Virtualmin Forums if you like.
Note though that the quickest and simplest way to backup your server to a secondary server is to generate a set of backups each night, copy them to the secondary server, and then import them into Virtualmin on that secondary server.