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domb
Contributor
Contributor

Where my RAM gone?

I have an ESXi host with 4GB ram running 1 virtual machine which has 2GB allocated. For some reason I only have 65MB remaining? Is this normal behaviour? I can't add the host to vSphere Center and I think it's because it doesn't have the RAM to install the tools. The error is 'Cannot install the vCenter agent service. Unknown installer error'.

This is how my memory looks.

Host Resources

Capacity: 4083.56MB

Usage: 2897.00MB

Resource Allocation

Total Capacity: 2279MB

Reserved Capacity: 2214MB

Overhead Reservation: 0MB

Available Capacity: 65MB

Configuration

Total: 4083.6MB

System: 558.6MB

Virtual Machines: 3525MB

Why under resource allocation is the capacity only 2279MB? Is my one virtual machine allocating all the available RAM to itself?

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J1mbo
Virtuoso
Virtuoso

It looks to me that the VM, or a resource pool, has a RAM reservation set on it.

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domb
Contributor
Contributor

That sounds about right to me! So on my VMs properties my resource allocationreads as follows:

Shares: Normal

Reservation: 2048MB

Limit: Unlimited

Should I set the limit at 2048MB? The most I can allocate under limit is only 2278MB anyway so where has the other 1GB RAM gone?

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J1mbo
Virtuoso
Virtuoso

Stop the VM, then change the reservation to zero.

HTH

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domb
Contributor
Contributor

I see. So the reservation is over and above what the VM is already using?

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jkumhar75
Hot Shot
Hot Shot

1.Stop the Vm and set the reservation to zero.

2.The remaining 1GB RAM is basiaclly used by the service console of the ESX server.

If you found this or other information useful, please consider awarding points for "Correct" or "Helpful". Jayprakash VCP3,VCP4,MCSE 2003 http://kb.vmware.com/
J1mbo
Virtuoso
Virtuoso

On ESX the "memory total capacity" on the resource allocation sheet is always about 1200MB less than the "Memory virtual machines" figure on the configuration, memory tab.

Basically, consider the footprint of ESX to be about 2GB. Since in the VM properties another 2GB has been reserved exclusively for that VM, there is nothing left. If you have vmware tools installed in the guest and no reservation, ESX can "get back" RAM from the guest through the guest's own paging mechanisms (or vSwapping, which is much harsher).

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domb
Contributor
Contributor

Thanks for your help! What threw me is that it said SYSTEM is using 558MB. Basically ESXi uses much more RAM than it says it is I guess... I'll stop the VM when I get a chance and reduce the reservation.

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