WordPress MU

I am about to buy my own dedicated server to host my Wordpress MU, but as it is running on a big server with a lot of other websites running simultaneously i don't know exactly how much resources it needs to run smooth.
I host 2000 blogs and have approx 4000 posts a day sitewide.

When i have my new server, will 1gb ram do fine with an 3ghz Sempron ? Or will I be better off with a bigger server?

Bigger, with some room to grow.

I wouldn't get less than 4G of RAM myself, if you already have the user level to handle it, you'll appreciate it now and down the road if you hit a spike or something.

Also, you'll want to stick APC on it as well, to help with caching.

"Especially" if you're going to be hosting other sites besides MU on it.

How important is CPU speed with Wordpress MU?

*chuckle* The servers that run wp.com are rather low in speed actually. Your 3 should be fine.

I'd opt for memory and a decent file system actually. RAID would probably help. I'd lean for the 4 gigs as well. I know my own hosting servers are all 4 gig, Intel 2.8-3.0 htz with hyperthreading. I'm hosting 200-225 seperate clients on each one without issue.

since i've started migrating some of my blogs to mysql 5, I've found it uses much less memory than my former 4.0. Depending on the version you pick with your hosting, you might want to take that into account.

quenting, are there a lot of changes involved in the migration to 5?

none that i've seen for MU.
1) mysqldump from old DB to file.sql (using mysqldump packaged in mysql 5)
2) mysql < file.sql into new DB
3) done
:-)

There's a couple of issues with other open source projects with MySQL 5 though. phpNuke I think has a couple.

@quenting

you seem to describe the situation when moving from a mysql 4 server to a mysql 5 one, but what if I update my debian 3.1 install to 4.0? that will include an update from mysql 4 to 5...

I hope they will release it soon :-)

I am sure that amd 3000 and 2 gb ram is anougth for 50.000 guest.
but if not, or your site be so big. then never mind to upgrade for ram.
use 2 servers .
1 server for mysql
1 server for php.( you can install Lighttpd on this server for pictures. I mean apache + Lighttpd )

and if you can , use 3 servers
3th server for picture uploads..

oh yeah i was mentionning upgrading tzo a new server too, not just upgrading the software on a single machine, this i have no clue about how easy the migration would go.
You could try mysqldumping your whole DB, than upgrade mysql, than see if it works and if it doesn't (it should though) reload it from the dump. I can't certify that works though, since I've used the mysql5 dump and maybe it did take care of the differences for me. The DB schema for wordpress is really simple though, so unless you've been playing with charsets and stuff I don't see why there would be such differences.