Three esx servers or two esx servers?

[matthew_mcdonal]

We currently have three esx servers (dual dual core, 16gb) connected to a Hitachi SAN. We're in the process of replacing these servers with replacements and we have two options to meet our requirements of around 12GHz of CPU and 64GB. We run around 20 virtual machines which are a combination of windows servers running exchange and file and print and redhat running oracle and jboss.

Option 1: 2 x higher end dual quad core servers with 32GB each

Option 2: 3 x lower end dual quad core servers with 24GB each

Both servers are the same model but different specs, one is a high end server. The three servers work out around 20% cheaper.

We're reusing the FC HBA's, we already have three ESX licenses and we manage the servers using VC so there's no additional costs to go the three servers (except the maintenance cost each year on one esx server).

The benefits I see of having three servers are;

• 12 cores as opposed to 8 cores

• n + 2 redundancy for core servers

• 66% capacity left after one failure as opposed to 50%

• cheaper servers and cheaper maintenance as warranty can be reduced from same day to next day

• easier upgrades to new versions of esx as a server can be taken offline and still leave redundancy

• 50% increased bandwidth to SAN

• 50% increased bandwidth to Network (18 NIC's as opposed to 12 NIC's

I can't really see any drawbacks to having three servers?

My boss however likes the idea of two servers and I need to convince him, if anyone has any information that would assist in my case I would greatly appreciate it.

[davidbarclay · Accepted solution]

On the surface it's easy to say, go the 3 server option...as you correctly pointed out the technical benefits. However, it's easy to underestimate the cost of that 3rd server. Sure you have a sunk cost in the Vmware licensing, but you still have year 2 and 3's cost. Same goes with the server, support costs for 3 years, power and cooling for another 3 years etc

It's probably not a huge number, but your boss is probably thinking along these lines. Perhaps you need to knock up a quick spreadsheet to calculate these costs, then compare this cost against the benefits you've mentioned. Until you do this, your boss will probably have his way

I'd focus on availability and additional capacity. Capacity is an easy one to align with costs, so start there. Availability is important too, but harder to quantify.

Good luck.

Dave

[matthew_mcdonal]

Thanks David,

My boss has just approved three of the 32gb high end servers :smileygrin: which I'm more then happy to go with, memory is always in short supply!

The areas that sold him were mainly the extra bandwidth to the SAN and the extra bandwidth to the Network.

Regards

Matthew

[mreferre]

Matt, I would have gone with 3 servers too for this specific scenarios.

However, generally speaking, more bandwidth (do you really need it? I doubt) also means more cables and more FC / Eth ports on the infrastructure (to the extreme that if you don't virtualize you have a MUCH HIGHER bandwidth as each of the physical server has its own way to the infrastructure - this doesn't mean though it's the best choice).

For a such a small deployment though three servers is a good number (especially for maintanance and HA concerns).

Massimo.

[davidbarclay]

Whatever works for ya...

I've just recognised your name...I hope things are going well. Just send me the PO

Dave