Auto redirect if server is down

rbalaa · 07-20-2011, 12:27 AM

Hi All,

Can I get some advice on where to look for setting up my web server A so that if I have to bring it down for maintenance, all web traffic will go to my backup server B. I thought about changing DNS entry but that will take time to update.

Thanks for your help in advance.

SL00b · 07-21-2011, 08:57 AM

Here are some options, each with their advantages and drawbacks.

- DNS updates can be scripted with the nsupdate command, but yeah, depending on the TTL of the A record, it can take a while to propagate. You could resolve that by issuing the nsupdate command, giving it some time to propagate, and then shutting down server A.

- If what you're looking for is instantaneous failover, you could look into a load balancer. There are software solutions for that, but they end up facing the same problem... you end up doing maintenance on the load balancing server. It's usually done by setting up another apache server as an http proxy.

- Big business tends to use an appliance for this function. They're not cheap.

rbalaa · 07-21-2011, 09:59 AM

Quote:

Originally Posted by SL00b

Here are some options, each with their advantages and drawbacks.

- DNS updates can be scripted with the nsupdate command, but yeah, depending on the TTL of the A record, it can take a while to propagate. You could resolve that by issuing the nsupdate command, giving it some time to propagate, and then shutting down server A.

- If what you're looking for is instantaneous failover, you could look into a load balancer. There are software solutions for that, but they end up facing the same problem... you end up doing maintenance on the load balancing server. It's usually done by setting up another apache server as an http proxy.

- Big business tends to use an appliance for this function. They're not cheap.

Thanks for your input. I think I'm goign to try duplicate IP for one domain name. Then disable round robin. And lower the TTL to 1/2 hour.