SQL Failover - Mirroring, Log Shipping, Clustering, Load Balancing

Hello.



I am confuse and cant decide on how to setup high availability on our SQL 2005. Here's what on my mind and on resources list:



I plan to have mirroring on my SQL1 to SQL2 with the help of SQL3 as witness. So this would be automatic failover. My idea on mirroring is when SQL1 goes down, SQL3 would tell SQL2 to run and be the primary. It will automatically failover to SQL2. Right? My questions are:

1) How can I revert back to SQL1 once it is ready?

2) I read in one of the post that it is impossible to write in a mirrored DB, is this true? I mean, what's the use of failing over to the next node when it's not possible to write and update data/records?

3) If number 2 is false (i hope so), how would the data be synchronize from SQL2 back to SQL1. Those transaction that were made while SQL1 is down.

4) How about the connection string from the web applications? Would it be automatically point to SQL2? We have load balancing setup in place, would this help web application connection to automatically point to SQL2?



Another setup:



We have SAN in place (not yet used, but is planning to use for this SQL thing), EMC to be specific. My question would be:

1) For SAN setup, the data storage would be centralize. So would that mean that SQL1 and SQL2 services will use the same data and log file from the SAN storage?

2) How would you call this setup then? Can this be clustering type of high availability? Will clustering work under load balancing setup? I believe mirroring is not possible here? Right?

3) How can I setup my 3 SQL servers with the same theory in mind: when SQL1 goes down, SQL2 will take over. Data will be synchronize when SQL1 is up and running again. With automatic failover and reverting back to primary.



I read so much topics about this, but the more I research, the more I get confuse.



Any suggestions, comments, advice is greatly appreciated!