2012 R2 Hyper -V memory issues

[Alis_Klar]

I have two physical servers bith with Windows Server 2012 R2 running hyper V guests.

 

1st server has had loads of VM's with no problems

2nd Server is newly installed, hyper V role newly added, created new 2012 R2 guest and allocated 4096 MB startup RAM. Guest is consuming all that RAM.

 

changed strtup ram to 8192 MB it still consumes all the available RAM. But hyper V reports that is is using 895MB of RAM from the host's perspective.

 

I am applying updates as I type to see if an update will fix the issue.

 

Will try disabling dynamic memory next.

 

EDIT

 

Just to clarify. What was confusing me was that the guest was claiming it was using 8GB of RAM but hyper V manager was only assigning just above the minimum RAM. The guest was newly installed not doing anything. No matter how much startup RAM I gave it it consumed all of it but the assigned memory didn't change. Is this normal for dynamic memory?

Edited May 21, 2015 by Alis_Klar

[Steve21]

StartUp RAM is the lowest it can ever go (stupid logic of MS imho). So if it's set to 8GB it'll always use 8 minimum

 

If that's what you mean that's "expected" if you want it to use less, put lower startup, and then higher max.

 

Steve

[tmcd35]

In performance manager, on the guest, is the memory reporting 100% usage?

 

Windows mearly thinks it's got 4096mb installed. Dynamic Ram will reduce that only if a) the memory is needed by another VM, b) the machine isn't using it all, and c) it's not the minimum allocation limit for that machine.

 

The guest will report full allocated memory as being available so long as those three conditions are not met. Start up a few more demanding VMs with bigger minimum memory requirements and see what happens.

[Alis_Klar]

The allowcated memory 1606MB in hyper V is less than the startup RAM 4096MB !!

 

Host View

 

Guest View

 

Edited May 21, 2015 by Alis_Klar

[Arthur]

For guests that run SQL (or Exchange) you should have Dynamic Memory disabled.

 

www.aidanfinn.com/?p=11139

http://eightwone.com/2011/03/14/exchange-dynamic-memory-dont/

Edited May 21, 2015 by Arthur

[Alis_Klar]

Turning off dynamic memory had the effect I was expecting.

 

-Memory Usage in guest changed to 10% from 97%

-Allocated memory in hyper-v manager changed from 800MB to 8192MB

 

If dynamic memoery is enabled you see the following warning

 

"This virtual machine is configured with uniform memory access. Virtual machines configured with a large amount of memory or many virtial processors can often benefit from non-uniform memory access.

Disable Dynamic Memory to allow non-uniform memory access"

[Alis_Klar]

This guest will be used as our SIMS server so guess i'll disable dynamic memory for good!

[zag]

Yep always disable dynamic memory with SQL server, it will eat everything you throw at it!