I'm contemplating setting up a Master-Slave replication for my database. The slave server will be used for redundancy and possibly a reports server. However, one of the biggest issues I'm running into is that we're already maxed out on power at our datacenter. So adding another physical server is not an option.
Our existing database server is fairly under-utilized as far as cpu (load averages never really get above 1 on a quad-core). So the leading idea is to toss in some new drives and double the memory (from 8GB to 16) and run a second mysql instance on the same physical machine. Each instance would have separate disks for the database.
Is there anything wrong with this idea?
Edit (more info): I've (luckily) never had anything bad enough happen to take down the server, but am trying to plan ahead. We of course have nightly backups that we could recover from. But I figured having the redundant data on separate disks would provide a quicker solution if the master server's drives failed (obviously not if the entire machine goes out).
As for the reporting aspect, any tables we would report off of are MyIsam. So doing expensive reads on the same tables that are being written to can bog down the server. My assumption was having a slave server to report off of wouldn't affect the main server as long as we threw enough RAM at it (since cpu load hasn't been an issue yet).