Solved

Core Server - minimum space

Posted on 2011-03-04
10
468 Views
Last Modified: 2013-11-11
How do I calculate the RAM needed by a Core Server running HyperV VMs? Is it dependent on the RAM's consumed by the VM's hosted on it? I will give a couple of scenarios to illustrate the point.

Scenario 1:

Server 1 - 16 gig of physical RAM

VM 1 - 6 gig

VM 2 - 4 gig


Does this mean I have fully 4 gig of RAM left for the Core or is there some overhead of some kind e.g. paging for each VM which then means less than 4 gig left for the Core?

Scenario 2:


Server 1 - 16 gig of physical RAM

VM 1 - 6 gig

VM 2 - 4 gig

VM 3 - 5 gig

This would leave 1 gig for the Core but because I have more RAM in total and more VM's does this impact how much RAM the Core has for itself?


0
Comment
Question by:lineonecorp
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 6
  • 4
10 Comments
 
LVL 13

Accepted Solution

by:
Felix Leven earned 500 total points
ID: 35041016
First Game has changed on Hyper-V since Sp1, because of the DynamicMemory Function.
http://technet.microsoft.com/en-us/library/ff817651(WS.10).aspx

At the end of this Article you find an appendix listing the recommended Startup RAM for supported Servers in Hyper-V.

just to be sure the new memory feature won't take away to much memory from the parent host (?1024MB? standard), you can set:
HKLM\Software\Microsoft\Windows NT\CurrentVersion\Virtualization
to 2048 for example,
0
 
LVL 13

Assisted Solution

by:Felix Leven
Felix Leven earned 500 total points
ID: 35041029
sry

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Virtualization\MemoryReserve
decimal REG_DWORD
0
 

Author Comment

by:lineonecorp
ID: 35041043
Interesting but what I am more interested in is how much memory do I need to leave for the Core and how that's related to the number of VM's and the RAM they've been allocated. Is 1 gig of RAM left for the Core in example 2 or do I need more? Would I need more left of the Core if I had 32 gig of physical RAM and 31 gig in guest VM's? Or will 1 gig or 2 gig do no matter how much physical RAM I have and how many VM's are consuming it?
0
Edgartown IT Case Study

Learn about Edgartown's quest to ensure the safety and security of the entire town's employee and citizen data. Read the case study!

 
LVL 13

Assisted Solution

by:Felix Leven
Felix Leven earned 500 total points
ID: 35041097
i don't think you need more than 1 G of ram left for the parent host in case you install just three servers (or 10-15 Servers). care more about the sizing of the VM you will install. what services will be installed, mail, db, webserver. do you need a second server for live-migration in case of an upgrade to the server hardware/desaster recovery.
0
 
LVL 13

Assisted Solution

by:Felix Leven
Felix Leven earned 500 total points
ID: 35041123
memory overhead of each VM is 32 MB for the first 1 GB of virtual RAM plus another 8 MB for each additional GB of virtual RAM + 512MB ParentHost

MS Performance Guides now include Hyper-V:
http://msdn.microsoft.com/en-us/windows/hardware/gg463392
0
 

Author Comment

by:lineonecorp
ID: 35073091
So if I have 5 VM's each with 3 gig of virtual RAM  I would need:

32 meg for the 1st gig of virtual  RAM for each VM  * 5 VM's = 160 meg of VM overhead RAM

8 meg of RAM for each gig of  the remaining 2 gig of RAM in each VM for a total of 16 meg for each VM times 5 VM's = 80 meg of VM overhead RAM

So total overhead RAM in this scenario would be 240 meg of RAM

I would also need 512 Meg for the host Core server

So in total in this scenario I would need 752 meg of RAM above and beyond the 15 gig of RAM for the VM's.

So 16 gig of RAM in this type of system would be adequate?

0
 
LVL 13

Assisted Solution

by:Felix Leven
Felix Leven earned 500 total points
ID: 35073252
Yes, 512 mb hyper-v + recommended memory for the server edition you are using, but with the right configuration of dynamic memory you can free more memorye for future use. But keep in mind This is the theoretical view, for standard workloads (services your vm's offer).
0
 

Author Comment

by:lineonecorp
ID: 35073331
Sorry not following.  Were my figures correct?  752 meg of RAM above and beyond the 15 gig of RAM for the VMs?
0
 
LVL 13

Assisted Solution

by:Felix Leven
Felix Leven earned 500 total points
ID: 35073474
Yes, there will be some small tweaking here and there but it will be ok.
0
 

Author Comment

by:lineonecorp
ID: 35073861
Thanks.
0

Featured Post

Office 365 Training for Admins - 7 Day Trial

Learn how to provision tenants, synchronize on-premise Active Directory, implement Single Sign-On, customize Office deployment, and protect your organization with eDiscovery and DLP policies.  Only from Platform Scholar.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Remote Apps is a feature in server 2008 which allows users to run applications off Remote Desktop Servers without having to log into them to run the applications.  The user can either have a desktop shortcut installed or go through the web portal to…
Restoring deleted objects in Active Directory has been a standard feature in Active Directory for many years, yet some admins may not know what is available.
This tutorial will walk an individual through configuring a drive on a Windows Server 2008 to perform shadow copies in order to quickly recover deleted files and folders. Click on Start and then select Computer to view the available drives on the se…
This Micro Tutorial hows how you can integrate  Mac OSX to a Windows Active Directory Domain. Apple has made it easy to allow users to bind their macs to a windows domain with relative ease. The following video show how to bind OSX Mavericks to …

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question