I'm considering the following setup:
- 2 virtual servers with local C: drive
- 1 filesystem on a SAN
- Database server software installed on both, database on the SAN filesystem
- 1 virtual server does production, the other one is a spare server
- Both virtual servers are configured to be 100% identical, except for IP address, and only one of them may be connected to the SAN filesystem at the same time
This way, when upgrading/patching the database server to a newer version, we could do this:
- Upgrade the spare server's database server software
- Disconnect users
- Move primary server to a different IP address and disconnect from the SAN filesystem
- Move the secondary server to the production IP address and connect to the SAN filesystem
- Reconnect users, so that they now use the secondary server
- Upgrade primary server's database server software
After this, the roles are switches, making the primary server become the spare, and vice versa. As far as I see it, the total downtime for this should be a few seconds.
Is this a viable setup? Are there any things that I should be careful about?