iChat Load Balancing or failover solution?

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iChat Load Balancing or failover solution?

Hello, I am working a plan to develop a iChat server. I think a Mac Mini would be a good start for a group of 50 users. The users are all over the country and my role is to unite them all in a iChat domain. I thought about building two Mac Mini servers and have them run a same domain where all users are registered in. So, we would not be impacted when one of them goes down.

Anyway, the question is how can I have a load balancing or failover solution for the iChat domain?

Mac Mini, Mac OS X (10.6.5)

Posted on Jan 3, 2011 8:19 AM

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Answer 1

Net0maN Author

Level 1

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Jan 4, 2011 9:22 AM in response to Net0maN

Hello, its me again. I took time reading Server Admin Help for Mac OS X Server's iChat and Open Directory and I drew a rough diagram. Please correct me if my suggestion is not a good solution or technically feasible. What I am going to explain below is how I think is best to load balance or failover my company's iChat service. Technically, it is not the best solution but I believe it works with Apple technologies. I was instructed to build the solution with Apple's products.

I am going to build two Mac Mini servers and have them both in a same domain. One of them will be primary domain controller and the other backup domain controller. The open directory will manage user accounts for iChats and have both servers replicate them. Both servers will serve iChat for the users to login and collaborate with each other. They will be linked using 'XMPP server to server federation'. Finally, users in both iChats servers would be able to collaborate with whoever in a same buddy list.

I will request both servers to have a same domain name with different IP addresses. For instance; iChat.HelpMe.com and 123.123.123.123 and 123.123.123.124 (fake domain name and IP addresses). The round-robin DNS will have two entries for the servers and forward half number of users to one server and the other half to the other server.

This is so far I managed to read and gather information together. Is there something I missed that I need to be aware of?

Question:
When one of either servers crashes, would a user's Mac automatically reconnect to the other server?

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Answer 2

Tim Harris

Level 4

1,481 points

Jan 6, 2011 4:22 PM in response to Net0maN

On the issue of load balancing, whilst I don't have any experience with macMini's, you will not need to worry about load balancing with 50 users. I'm sure you can probably put a few naughts on the end of that before you need to worry.

The design you are proposing will not work for iChat services / and for that matter most of Apple server services. For high availability services (e.g. transparent failover) I think you are going to struggle to get this working and it 'seems' Apple no longer offers guidance on this subject on 10.6.x.

You will increase availability by using an Xserve with dual PSUs and raid disks. If you are only running high availability ichat services, I would buy a pair of second hand xserves with 10.5 OS and set the ipfailover services running. Personally I would buy one and a service kit and not bother with HA - as you will find the servers are very reliable.

If you have to use mini's then just have one live and keep a near constant clone of it on another ready to manually swap out if you have a hardware failure.

Your proposed design will not work without a lot of effort non of which is supported by Apple - although it would be rewarding if you did get it working. You cannot have server to server traffic for the same domain as all your application data needs to be stored centrally. OD only provides services for authentication. The ichat server also has its own data store and this is not distributed nor can it be. It is possible to move the data store over to say an enterprise version of mysql and have that distributed.

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Answer 3

Net0maN Author

Level 1

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Jan 17, 2011 7:39 PM in response to Tim Harris

Gotcha. I'll start small and go from there.

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