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Re: [Linux-cluster] High availability mail server



Samer ITS wrote:
Dears

I have 4 servers. And I need to install high availability mail system (Postfix, Dovect, Spam, mailscanner, ….)

Best regards

Hi Damer,

  Hi have to agree with Finnur, if in idea and not tone. :)

Clustering is not very easy. It is complex and, as I've learned myself over and over while learning it, it is very easy to break. You need to understand how all the parts tie together so that when you do need to change something, you know how the other components will react. There is no simple canned solution around this -- It's just too small a segment of users.

  Answer these questions;

a) What if your goal with clustering? Performance? Uptime? Scalability?

b) These four servers, do they have mechanisms for fencing like IPMI control boards?

c) Do you understand terms like Heartbeat, Cluster-aware file systems, iSCSI/SAN/NAS, Fencing, Split-breain, Quorum?

d) What operating system and what cluster tools do you plan to/want to use?

I'm not trying to discourage you from clustering, honestly. I am, however, trying to keep you from getting in way over your head. I've been playing with clustering for a couple years now and I still constantly run into issues for no other reason than that I simply didn't understand the systems well enough.

As for your specific application; Have you though about how you are going to handle user authentication? Will you need to support multiple domains?

You have a *lot* of variables you need to sort out in the mail system alone before you can start worrying about the cluster component.

If you have a short time line to launch, hire a consultant who is already familiar with clustering. If you have lots of time, start reading and then come back here with specific questions, including steps you've tried, specific errors you've run into and so on. You will find this list very helpful when you show that you've put some effort into your system already.

Best of luck!

Madi


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