Setting up a mirror on another server.

[frost]

Greetings,

We have recently decided to set up a mirror of our site on a second server in the event of an outage on server #1 and I was looking for some assistance and clarification on the best practices for this...really dumb it down

The DNS

As I understand it what should be done is DNS2 should be set to the ip address of the site on server #2. If DNS1 times out, DNS2 kicks in and the user would end up at server #2. Is that correct?

If server #1 comes back online will users that are on server #2 be directed back there on a page change?

Databases

We use a mysql database to keep customer records, if they end up on server #2 how can we synch up with server #1? For example there are several auto increment fields.

Any input on this would be great, thanks in advance.

[wige]

As I understand it what should be done is DNS2 should be set to the ip address of the site on server #2. If DNS1 times out, DNS2 kicks in and the user would end up at server #2. Is that correct?

Yes, for a basic redundant setup, that should be correct.

If server #1 comes back online will users that are on server #2 be directed back there on a page change?

No. The client will cache the DNS information from the first request, and will only refresh that information after a set (client determined) delay or if a subsequent request fails due to a timeout or BAD REQUEST/BAD HOST response.

We use a mysql database to keep customer records, if they end up on server #2 how can we synch up with server #1? For example there are several auto increment fields.

This will really depend on your server and network architecture, as well as the type and volatility of the data you need to synchronize, as well as several other factors including budget and ssecurity considerations. For instance, in some setups a nightly synchronization will suffice. In other cases, transaction-based synchronization would be necessary.

[frost]

Thanks wige, I appreciate that info.