VMware Server and ESX - server specs

[christoph at linuxsoup.com (Christoph)]

On Tue, 2006-10-03 at 18:32 -0400, John Abreau wrote:
> I'm looking to buy a 1U or 2U server to run VMware on. My initial goals
> are to migrate a recently retired NT4 finance server into a guest OS,
> and to install a Scalix groupware server in another. 
> 
> I also want to be able to build several additional production servers
> within it, as well as use it for test servers whenever I need one. 
> 
> I guess the biggest questions initially concern CPUs and hard drives.
> VMware's web site suggests that 4 guest servers per CPU should work
> reasonably without serious performance issues; how accurate is that
> claim? Can I count on a decent number of guest systems with two
> dual-core Xeon CPUs, or do I really need four?
> 
>  If I use SATA hard drives instead of SCSI, how will that affect
> performance? 
> 
> Clearly I'll want gigabit ethernet, not just 100baseT. 
> 

You didn't mention memory ... that should be your #1 issue.  Many dual
socket servers don't have enough slots for lots of memory.  Make sure
you add that to your formula.

If you put production guests on the system, you'll also likely want
hardware raid which (IMHO) voids concern of SCSI vs. SATA.  You just
need to ensure you are using supported hardware.  I can't imagine you'd
invest in ESX, and cheap out on SPOF prevention.  Hardware raid, dual
power supplies, etc...

But what you stated is fair, (IIRC) performance overhead for VMWare is
about 10-12% (yymv) and the rule of thumb is 4 to 1.  However if you
have an app that taxes a stand alone box at 100%, it'll tax the VMWare
host the same.  So, that brings the key point .... you need to
understand your apps.

-cfd


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