Memory Active/Usage

[navtek]

Hi,

I have reserved 512Mb for a windows 2003 server. Having looked at some memory counters (Active, Shared and Assigned) I have noticed that there is approx 300Mb of active memory and 1500mb of shared memory. My questions is how much of my reserved memory is in use? I want to make sure that my server has memory allocated to it whenever it needs it and that I don't over allocate too many vm's in the cluster. I also want to track the amount of free memory in the cluster.

Also if I initially assign 5000MB (previos physical server) to the vm and it only has the 300MB active, from myunderstanding the remaining 4300MB is available to other vm. Or is a better way to change the assigned memory to reflect the active memory eg assign the vm 512MB

Hope this makes sense

[virtualdud3]

If you grant a VM a memory reservation, it really does not matter how much of the reserved memory is "in use", as whether or not the reseverd memory is "in use" it will not be available to other VMs.

Again, whenever you grant a VM a memory reservation, that physical memory is NOT available for other virtual machines, even of the VM to which you have granted the reservation is powered-off. So, in your example, if you assign 512Mb of memory to a VM, and that VM is only using 300Mb of memory, the 212Mb of physical RAM is NOT available for use by other VMs.

[RParker]

"even of the VM to which you have granted the reservation is powered-off."

I agree with everything you said but that. This is not true, the reservation is ONLY active for VM's powered on. It makes no sense to reserve memory for a resource that isn't active.

And you can prove this point by powering on that VM, and if there is NO memory available to power it on, you will get an error message that there isn't enough memory, which proves the point that it's NOT reserved while off.

Everything else you said is excellent however.

[nayudu]

Perfect. When a VM is powered off Memory reservation set or not set it wont have any affect on Physical Memory.When you power it on , It will power only if the set reservation value is available in physical pool.If it is not there will result in a error ,if it is there it will be locked exclusively for that VM.

Regards

Kishore

[navtek]

Thanks for getting back to me. what I'm trying to gather is how much memory I should reserve. I understand that memory reserved is private to that vm as long as it is powered on. However how would I size my memory reservation so that I am not reserving too much memory for the vm. Initially

I setup the reserve as per my stats off the physical machine however now that I am dealing with Active and Shared memory I dont know where to size it from here and what to measure the current memory reservation.

For example if I have reaserved 1000mb of memory I want to make sure that 70-80% of that reservation is in use otherwise I might be able to drop it back to 850-900.

Thanks.

[nayudu]

I would say you should go for the value which is recomended for your OS.Like Win2k I think it is around 256Mb

Regards

Kishore