database question
 

We are starting two new sites and both have MySQL databases.

Would it better to use:

2 servers for each database with replication

OR

4 servers for both databases with replication

I've gotten different opinions and want to see what GFY techies think.

Thanks!

I would say 4 with replication. Only because I have seen several companies do it this way as opposed to having dbs on seperate servers.

1 server with a scsi raid-5 array
Hotswap drives
Dual power inputs
Make sure the card supports on-the-fly reconstruction of the array
multiple nic cards

set up a couple of web servers using DNS Round robin and you're good to go

Uh...

This doesn't answer his question at all :warning


But yeah, I'd go with the 4 replicating as well, you'll kick yourself later if one site uses a lot more resources than the other site, and hardware is sitting there idle when needed elsewhere.

Depends. What is the read to write ratio for each site? If you're doing relatively few writes you're probably better off with 1 master and 3 slaves. If you're doing lots of writes, go with 2 masters and 2 slaves.

Also, don't overlook the value of http accelerators (reverse caches) on heavily dynamic sites.

you shouldn't need more than one dedicated mysql box. fire your programmer, now.

just steal an idea from someone

Depends on the number of queries and the amount of data stored don't you think?

Exactly
Or 1 goes haywire and goes down, youll go SHIT I wish I had another backup.

No, he's right, better to get ONE BIG server to do it all.

It'd be more efficient to run web and database on the same server too!

How do you figure one server is better? Replication allows you to tailor each servers parameters to the needs of the client. Some queries run slow and infrequently, others run fast and often, and you've got writes which are a whole different issue. One configuration will probably not work the best for all queries. It also gives you redundancy and allows you to get much more bang for the buck. Do you get more processing power from one $10K server or ten $1k server?

As for web and database on the same server, if you're running a small site it certainly is more efficient. If you're doing any sort of traffic you're best off running them seperate (and probably running seperate webservers for static and dynamic pages). Any savings by running both on the same server are miniscule. Not to mention if you're that concerned with efficiency round robin dns is NOT the way to go.