New to virtual server management...

boss99

boss99

2[H]4U
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Dec 29, 2006
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After reading Sabregen's excellent write up, I felt inspired to build a small ESX lab for home to expand my knowledge. I'm a junior network engineer by trade, but I have roots in help desk and some server management, so I wanted to give it a shot.

Here's my hardware setup:

eVGA 680i
Q6700
8 GB RAM
Dell PERC 5i
4 x 1 TB SATA
2 x 146 GB SAS
1 x 40 GB SATA (for host OS)

I'm planning on using ESXi without any failover or vmotion since it'll be the only box in the cluster, but I was wondering if there was a beginner's guide for provisioning hardware for the VMs. Since there are only 4 cores, can I only have 4 VMs running at one time? I apologize for being such a noob, but I think if I can get a toehold into this, I found this section of the forum to be fascinating and something I can hopefully get off the ground.

Thanks in advance.
 
You can run many VMs on a single physical core, it's not a 1:1 mapping. Not unusual to have 100 VMs on a system with 12 cores. It all depends on the workload as to how many physical cores you need.
 
Memory will probably be an issue before the CPU... to make VMs run decent you have to give them a respectable amount of memory.
 
That is something I can understand. Thanks guys for the clarification.

So the CPU can juggle between multiple VMs, but memory doesn't then?
 
Well..kinda. :) A CPU executes threads. If a VM is idle then the CPU can process other VM's threads. So it's just doing work. Memory holds information. So it doesn't hold one VM's data and then another and another. But...memory is only used if needed. If you assign a VM 4GB but it's only using 2GB then only 2GB of real memory is used. If they are both Windows 2008 then it only keeps one copy of that in memory at a time (known as page sharing). So you can "over commit" memory.
 
Although I seem to recall that some guests seem to suck up all of the memory (I think FreeBSD might be one of them?)
 
NetJunkie said:
Well..kinda. :) A CPU executes threads. If a VM is idle then the CPU can process other VM's threads. So it's just doing work. Memory holds information. So it doesn't hold one VM's data and then another and another. But...memory is only used if needed. If you assign a VM 4GB but it's only using 2GB then only 2GB of real memory is used. If they are both Windows 2008 then it only keeps one copy of that in memory at a time (known as page sharing). So you can "over commit" memory.
Click to expand...
You know you said it way easier than I could have said it, great post!
 
I though ESXi held the memory? I thought "Thin Provisioning" of RAM was only in ESX
 
Jay_oasis said:
when did that change?
Click to expand...

Never knew that to be the case. Just looked at a KB article comparing ESXi and ESX on 3.5 and the differences were just the usuals... Service Console and some other minor things. Now all new development is going to ESXi. Will be no more ESX.
 
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