Hyper-V virtual machine RAM performance shows 95% used but I can't find where

Posted on 2014-09-03
Last Modified: 2014-11-12
Hi everyone!
New question:
When I remote into a Hyper-V virtual machine, it shows that it's currently using 95% RAM doing nothing but sitting at the desktop and running a few IIS COM objects intermittently. The virtual machine has 8 GB of RAM allotted to it.
When I remote into the physical machine that hosts the virtual machine and look at the Hyper-V stats it says:
Startup memory: 8192 MB
Dynamic Memory: Enabled
Assigned Memory: 1155 MB
Memory Demand: 958 MB
Memory Status: OK

So this VM appears to be using somewhere in the neighborhood of 1.2 GB of RAM but yet when logging into the Hyper-V virtual machine, it appears it's using almost 7.5 GB.

Is it possible the virtual machine is showing that because it was initially allotted almost 8 GB so that's what it claims it's using?
Question by:HbugProject
LVL 58

Assisted Solution

by:Cliff Galiher
Cliff Galiher earned 250 total points
ID: 40302359
When using dynamic memory, memory usage statistics in the guest become completely useless. You can't use the percentage as an indicator of startup memory used because the Hypervisor will hot-add memory as needed (and yes, the kernel is aware of this.) What you describe is nothing to worry about since the Hyper-V Manager is, in fact, reporting only 1GB used. Hyper-V also adds several performance counters that can be monitored via performance monitor, SCOM, or SCVMM to get a more detailed view of memory usage and trends if you want that sort of thing. But for now nothing you mentioned raises a red flag to me. You'd want near full memory utilization, especially with dynamic memory. If it weren't then it'd be a sign that you've overallocated memory or that it isn't properly making dynamic adjustments.
LVL 20

Accepted Solution

Svet Paperov earned 250 total points
ID: 40302365
You can ignore the reading of memory usage inside the VM. Keep a look on the Memory demand and Assigned memory values in Hyper-V Manager.

Startup memory seems a little bit higher is the machine uses around 1.2GB. In case the RAM resource is limited this high value could prevent the machine from starting-up. I would put a lower value for Startup memory, something around 4GB but higher value for Minimum memory, may be something around 2GB, just to prevent Hyper-V from constantly changing the allocated memory.

Author Closing Comment

ID: 40302374
Thanks guys for calming me down on this one.
Yes Svet, I will adjust the "startup memory" and "minimum memory" just to be safe. This was my first go-around with Server 2012 and Hyper-V and I guess I misunderstood the startup memory, I just wanted it to have 8 GB available if it needed it because I know this server will taxed quite a bit throughout the day.
Thanks Cliff for mentioning SCOM, I will look into that for a more detailed stat of what "really" is taking place.
Thanks again guys!

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