VMWare Resource Allocation

Hi all,

Description of my home lab setup:

- ESXi 5.5
- One Server 2012 R2 Standard VM
- Three Windows 7 Pro VM's connected to the Server 2012's domain
- AMD motherboard that has IOMMU
- AMD 8350 CPU
- 32GB RAM

Clearly, the Server 2012 VM is the most important VM. I want to make sure I've got the settings correct:

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Go-BruinsAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
There is NO requirement for you to change any of the DEFAULTS!

You only need to change these resources, if your VMs are constrained.

and with FOUR VMs, and 32GB RAM, which is often the bottleneck, I would suggest before you start altering ALL the defaults, you reset to Defaults, and performance will be fine.

I work with ten of thousands of VMs on a daily basis, and we do not have to change these resources UNLESS we find that a HOST is suffering with overall HOST resources, because there are TOO many VMs competing for CPU and/or Memory.

The hypervisor algorithm does this for you... if you change it, you will have to have spreadsheets, and change for all your VMs, manually!

e.g. do you really want to ring fence, and guarantee 16GB of RAM for your Server 2012 server, although it may not use it, but by placing a reservation, this prevents the hypervisor from allocating to any other VM, if required!

which it will only do, if resources are high on your host, e.g. you allocate  8GB to each Windows 7 VM!

If you are sensible with CPU and memory allocations of VMs, no need to use shares and resources, you will get your self in a mess!
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Go-BruinsAuthor Commented:
Great, i will follow your advice.
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Go-BruinsAuthor Commented:
Ok - I screwed something up. I put all the settings to default, but am getting this error msg:

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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Not enough storage space on the datastore.

When you power on a VM, it also creates a memory swap file called VSWAP file, on the datastore, equal to the amount of memory in the VM, or equal to the memory reservation specified.

1. Solutions include, increasing the space on the datastore.

2. reducing the memory in the VM

3. relocate the swap file to a different datastore.

see also here

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1030719

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2030250
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Go-BruinsAuthor Commented:
Thanks. I made sure I undid all my settings to default:

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but still getting error msg. I'll try the solutions outlined above. Good thing this is just a test bed.
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Go-BruinsAuthor Commented:
I was able to boot by reducing the amount of memory. I then tried setting it back to 16GB, which was my original setting that was working, but it failed again.

So I was left with creating a memory reservation:

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I realize this is happening because my datastore is full, but it's a little unnerving that I couldn't just go back to my working settings. I'm now left with a setting on one of my machines that's less than ideal. I guess the lesson here is that I need to leave some space on the datastore for such incidents.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
CORRECT!

You must always plan, and leave your datastores, with VM Space + Space for the SWAP FILE!

We woulds recommend, 20-25% being left free on the datastore for swap and snapshots!

You have probably found this now because you have a small datastore, and have powered up all your VMs!
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Go-BruinsAuthor Commented:
Valuable lesson learned...

Let's assume I use no snapshots (as recommended by many experts). Let's further assume the Server 2012 machine begins to fill up the allotted space on the HD. Will the VM blow up and stop working? Or will I see the typical Windows messages like "Your hard drive space is running low, blah, blah."?
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Go-BruinsAuthor Commented:
Also, is it possible to span a datastore to two or more drives?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
VMFS datastore is what you have to monitor.

You can span datastores, with two or more drivers.....

but not recommended, what do you think happens when a drive fails ?
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Go-BruinsAuthor Commented:
Good point. I'm learning in bunches. Thanks again.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
if you hadn't guessed, the whole datastore fails!

and once you add a disk, you cannot remove it, without the entire datastore failing, and being removed.

So, not recommended and dangerous!
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Go-BruinsAuthor Commented:
Yes, I was able to imagine that fiasco, lol.

Thanks.
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