Failover backup solution for IPswitch IMail

Hello, I recently joined a company and was named Email Administrator.  We are running IPswitch Imail server v. 11.5 and it is running on a new box with Windows 2008 R2 64-bit.  We host about 500 domains as well as about 5 of our own on this server with about 1000 users/email accounts.  My issue is that to do ANY maintenance on the server or email system, I have to stop the email services and shut down email to 500 domains, unacceptable.  The other issue is what if the server hardware fails, I am destined for being down for an unacceptable length of time to get back up and running.  Anyways, I have gotten the financial greenlight to go ahead and pursue a failover system with email redundancy, the question is what?  I do have an identical backup server that I would like to have mirror the original and be able to cutover to the backup server in case of disaster, maintenance, etc.  How do I create a failover system with the IMail server and what products will work with this email system to capture all settings and registry?  Thank you in advance for your suggestions!
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Sorry yes you do say that.

Mirror server setup is one way that I've looked at in the past but personally I would as you are using Windows Server 2008 setup it up as a cluster which can share the load and have a separate data store which hosts the mail data.

This is an example of the cluster setup:-

Or this may help but I know it's not cheap:-
A basic summary of what you need as I'm not fully up to date with the details is that ideally you need a server farm.

This means you would effectively have an identical server running the same operating system, software etc.

Setting up Windows Server correctly you would then be able to shut down one server and while the speed will probably be a little slower the service should still run as normal.

Ideally I would have at least 3 servers though and if you need to expand the server keep having an odd number of servers.

The data is probably better kept on a disc array to reduce cost. I don't believe it's necessary to have multiple copies of the data on different servers as a good RAID array and appropriate backup.
mjchevalierAuthor Commented:
Thanks winstonep but I am leaning towards finding a continuous availability software solution like NeverFail or NSI Double-Take, which have been recommended to me but I do not know what will work with an IPSwitch IMail Server?  Your solution sounds like a clustering solution?
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Yes that's right it is effectively a clustering solution.

If you really want to avoid service loss the only way you are going to be able to do it is with a second server of similar spec. After all if you lose the one you have got there is nothing.

If one server dies the other can at at least provide part of the service if not full service or if you need to take one down you can.

Your description mentions 500 domains suggesting the company is some kind of service provider. More hardware is the only choice of providing redundancy and offering the kind of availability that will attract customers such as 99.999%.

I worked at one of the ISP pioneer's in Britain around 12 years ago and there were server farms on different sites, load balancing and even different mail software used.

From this experience I strongly suggest that if you operate more than one site you should run two mail servers as a cluster on the main site and a third on another site that you have a fast connection to. With the three servers running as a cluster with one site down there is still service but the absolute minimum to avoid what has happened already is a second server on the same site.

Software can help sort out the failover but failover to what if there is no second server? Backup is critical just as is maintaining accurate build instructions so that the server setup can be re-created perfectly.

The choice is yours. It doesn't have to be clustering but this would make it all automatic. Server mirroring is another but I haven't come across this for a long time.

I hope whatever you choose works well for you.
Rob KnightConsultantCommented:

Double-take and similar solutions perform real time updates between the master and slave (or passive) servers and are designed to failover very quickly (typically less than 60 seconds).

In most cases, updates are deltas so work effectively over WAN links to DR facility.


That's right and it requires an additional server to provide the failover.

So yes you will need an additional server but this could be a DR server run by a third party or at another site that your organisation runs.
mjchevalierAuthor Commented:
Winstonep, if you read my original post you will see that I do have an identical backup server available for this failover solution. If needed, I also have access to additional servers but they would not be identical to the other two.
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