It appears that I'm at a bit of a crossroads right now. We're looking to implement vSphere 4 soon and I'm speccing out some servers. I can go one of two ways:
1) Two moderately powerful servers (2.9 Xeon, 64 gigs of RAM)
2) One powerhouse (4 Xeons, 128/256 (not sure yet) gigs of RAM)
I like the ability to distribute VMs across different hosts with the moderate setup, but my main concern is that it won't be powerful enough. I like the powerhouse idea in that I'll be comfortable with my specs and what I can do with it.
I'd love to hear everyone's opinion on this.
Personally I'd go with the 2 boxes and lob in the shared storage so you can use vMotion, HA & DRS to give you flexibility. I'd be looking at the age old addage, don't put all your eggs in one basket - what happens if your mainboard or a CPU goes and your left in a position where ALL your guests are down! With the 2 boxes and HA at least (given the resources) the guests on the failed box would be restarted on the other host.
Another point would be disk space. With the powerhouse box your putting together, how many disks/spindles can you cram in and how many controllers to spread the disk IO loads? If you've already got a SAN and you have the capacity then it doesn't matter, but if you've already got the SAN or getting one then I'd still go with the 2 boxes.
VMware isn't just about the ability to bung loads of servers onto one physical machine, it's about the other management options and feature rich functionality that makes up the whole package. It makes administraton so much easier and less of a head ache on a day to day basis and in a crisis!
Anyway, my 10p
Upon reading the thread a little deeper, I have to agree with Neil. If it's two ESX hosts, compared to just one, then I would choose the two setup, if you are using vCenter, which will give you the flexibility of redundancy.
...but if you can get two boxes of the larger hosts, then I say go for that.
We will be getting a SAN with this. I was leaning moreso towards the two servers, but I figured I'd get the communities opinion on it prior to throwing in my suggestions for servers.
Are far as drives are concerned, does anyone have any qualms (assuming we have a SAN) with using SATA drives in a RAID 1 for the vSphere setup? I'm imagining the server itself isn't really pushing much I/O, it's mostly the SAN.
I'd prefer 3(!) servers for failover capability. One server down = 33% resources lost. Compare it to 50% and 100%.
MCSA, MCTS, VCP, VMware vExpert '2009
Thanks for the help everyone. It looks like we'll be going with 2 (I asked for maybe 3, but I don't think it'll happen since we are only virtualizing a small percentage this year) hosts with 72GB RAM a piece.
Definitely go with two servers rather than just one. There will come a time where you'll have to do maintenance to one of the physical servers and you'll want the ability to VMotion the VMs over to the other server wtihout incurring downtime.
Also, you'll likely want to have VMware HA capability engaged and in the future, you may want VMware FT capability engaged and those will require at least two physical servers (preferably three for VMware FT).
Also, assuming your SAN is Fibre and IS a modern, enterprise-grade SAN, I'd boot from SAN rather than booting from local ESX hosts disks.
If your SAN is Fibre, get six physical NICs in each server (eight if iSCSI) so you can get redundancy for all the ESX functions plus be able to get a redundant, seperate VMware FT connection engaged in the future.