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Thread ID: 114189 2010-11-22 00:33:00 ESXi - Help with Memory Configuration WarNox (8772) Press F1
Post ID Timestamp Content User
1155187 2010-11-22 00:33:00 Hey!

Not sure if anyone here is experienced with ESX but thought I'd give it a try anyway :)

Working configuration:

Host sever: 5gb RAM

VM1: 1gb RAM
VM2: 2gb RAM

Datastore free space: 2.45gb

If I try to incrase the RAM of either so that the total for the two VMs adds to over 3gb I get a 'resource allocation error' when I try to boot up the 2nd VM. I would really like to know why this is happening since the server has over 4gb RAM?

I've set up a resource allocation for both VMs so that the swap file created is 0 bytes, as there isn't much space on the datastore, so that is not the issue. I do understand that ESX itself will use some of that RAM but surely not 1.5gb.

Hope someone can help :)

Thanks!
WarNox (8772)
1155188 2010-11-22 00:41:00 Hi ESX can over commit, so its not resourse per sa. How many CPU has the host?, i ask this as if dual socket, the RAM will be allocated half to each pCPU, therefore the most you can have depending on vCPU is 2GB....
ESX will only use 256-512Mb RAM itself....
SolMiester (139)
1155189 2010-11-22 01:20:00 The server has 2 CPUs:

Intel Xeon 3.2GHz
Processor Sockets: 2
Processors Cores per Socket: 1
Logical Processors: 4
Hyperthreading: Enabled

---

So does this mean the most I can give to one VM is 2gb? Both the VMs are set to use 4 CPUs.
WarNox (8772)
1155190 2010-11-22 01:30:00 What version of ESXi? inphinity (7274)
1155191 2010-11-22 01:39:00 The server has 2 CPUs:

Intel Xeon 3.2GHz
Processor Sockets: 2
Processors Cores per Socket: 1
Logical Processors: 4
Hyperthreading: Enabled

---

So does this mean the most I can give to one VM is 2gb? Both the VMs are set to use 4 CPUs.

Ahh, there's an issue right there, its not recommended assigning 4 cores to VM, especially when you only have 4 cores. The reason being that when a VM calls on its 4 cores, the other VM vCPU calls get queued!....
Secondly, the RAM is associated across the banks 2.5 to 1 pCPU and 2.5 to the other.

After the Host COS has its RAM, you are allocating RAM from BOTH banks back to 1 VM.....
Drop back to 2 cores per VM, ESX will distribute the memory via pCPU bank, and you should be alright!


If thats not the issue, check you havent got reservations adding more than the memory you have....
www.vmware.com
SolMiester (139)
1155192 2010-11-22 02:00:00 Cool, I will give this a try in a few hours. Will post back then.

ESXi version is 3.5 update 5, could not use 4 or 4.1 because of the whole 64 bit thing.
WarNox (8772)
1155193 2010-11-22 06:33:00 Ok so I shut down the 2 VM's, set both to use 2 CPUs but still can't boot with the following:

VM1: 1536mb ram
VM2: 2560mb ram

Screenshots of everything included below. I had a look at that PDF but still can't figure out what the problem here is.

Let me know if you need any more info and thanks again!
WarNox (8772)
1155194 2010-11-22 20:23:00 You'll have to post screenshot for me...of error message SolMiester (139)
1155195 2010-11-22 20:26:00 Ok so I shut down the 2 VM's, set both to use 2 CPUs but still can't boot with the following:

VM1: 1536mb ram
VM2: 2560mb ram

Screenshots of everything included below. I had a look at that PDF but still can't figure out what the problem here is.

Let me know if you need any more info and thanks again!

Your reservation is also the limit, see mine, limit is more than reservation, increase the limit of memory!
SolMiester (139)
1155196 2010-11-22 21:30:00 Error from the Event Log on the ESX server included below. Also included is a screenshot of the configuration I got to work. 1gb on one VM and 2.25gb on the other but anymore than that and I get the same error.

I set the limit the same as the reservation or a swap file is created on the datastore and there isn't enough space left on the datastore for this. Therefore I want to assign each VM a certain amount of physical ram.

What I got now works fine but I want to know why its not letting me assign more than 3.2gb since there is 5gb in the server.
WarNox (8772)
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