Who doesn’t like something for nothing? Step right up and enjoy Dynamic Memory! A free upgrade on your Hyper-V host computers and some updating of your guest Windows operating systems can yield over a 50% increase in the number of VMs you can run per Hyper-V host computer. Microsoft released Windows 2008 R2 SP1 (the first service pack for Windows Server 2008 R2), adding the Dynamic Memory feature on March 15, 2011.
Here’s a chart of what Dynamic Memory is doing for us on two Hyper-V hosts in our Odyssey Lab. Notice we have about a 40% “boost” in effective memory capacity on these hosts, and memory is money folks!
Table 1 – Dynamic Memory with VMM 2008 R2 SP1
|Quantity of Virtual Machines||Used Physical Memory||Host Physical Memory||Maximum Allocated Memory||“Dynamic Memory Capacity Boost”|
Dynamic Memory is an extreme value-add for current Hyper-V owners, who until now were limited by Window’s ‘share nothing’ approach to VM memory management. VMware ESX owners have had a memory overcommit feature for some time. Microsoft threw futile darts at the VMware approach, and after years of wait, adds a similar feature that lets virtualized Windows guests ‘see’ more total memory than is present on the physical host. Install Windows 2008 R2 SP1 using Windows Update or manually download the appropriate Windows 2008 R2 SP1 package at this link:
A must-read before deploying Windows 2008 R2 SP1 on Hyper-V hosts is the “Hyper-V Dynamic Memory Configuration Guide” at http://technet.microsoft.com/en-us/library/ff817651(WS.10).aspx. That reference includes these important tables:
- Support for dynamic memory by guest OS: this usually requires updating the guest Windows OS to the latest service pack as well as updating the Hyper-V guest integration tools.
- Recommended startup memory by guest OS: rule of thumb: 128-MB for 32-bit OS and 512-MB for 64-bit OS.
Managing Dynamic Memory with Virtual Machine Manager
You cannot use the original version of SCVMM 2008 R2 to manage Dynamic Memory on Windows 2008 R2 SP1 Hyper-V hosts. It is necessary to update SCVMM 2008 R2 to its own new service pack, SCVMM 2008 R2 SP1 released March 24, 2011. Once SCVMM 2008 R2 is updated to SP1 along with Windows 2008 R2 updated to SP1 on your Hyper-V hosts, you gain a powerful consolidated view of the Dynamic Memory status of all your VMs. Figure 1 shows a screenshot of the manageable attributes involving Dynamic Memory added by SP1 to SCVMM 2008 R2.
Figure 1 – New Dynamic Memory Settings
Notice that Startup Memory, Maximum Memory, Assigned Memory, Memory Demand, and Memory Status are displayed in the SCVMM console.
SCVMM 2008 R2 SP1 allows you to create and deploy VMs onto Windows Server 2008 R2 SP1 Hyper-V hosts, and will report on the memory currently in use for these VMs where Dynamic Memory is enabled. Using Dynamic Memory for supported VMs allows for more efficient utilization of memory, with consistent performance, and higher consolidation ratios.
Now, with SCVMM you can specify whether to use Dynamic Memory or not on a VM, and if dynamic, what the startup, maximum and buffer settings should be. Figure 2 displays where the Dynamic Memory feature is supported inside the New Hardware Profile wizard in SCVMM.
Figure 2 – Changing the Dynamic Memory Settings
After fully deploying SCVMM 2008 R2 SP1, and all necessary OS and integration updates, we have a full-up view in the Odyssey domain of all five of our current Hyper-V hosts and the 24 VMs running on them, merged into a single pane of glass—our private System Center development cloud, now more optimized than ever! This is displayed in Figure 3.
Figure 3 – The SCVMM Console showing all Hyper-V hosts and VMs
How to get SCVMM 2008 R2 SP1
There is no stand-alone upgrade package or Microsoft Update package for SCVMM 2008 R2 SP1. The only distribution vehicle for the service pack is in an integrated SP1 install of the complete SCVMM product, in licensed or evaluation editions. You can still do an in-place upgrade to SP1, but the download package is large—the whole, updated VMM product. The service pack is not available through Microsoft Update because there is an installer task that asks for DB credentials in order to update the VMM DB to contain the new settings for Dynamic Memory.
- Licensed owners of SCVMM 2008 R2 can download the SCVMM 2008 R2 SP1 integrated install media from Microsoft Volume Licensing sites, MSDN, etc.
- If you want to evaluate SCVMM 2008 R2 SP1, the download page at http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9189bbce-d970-4c6c-9dd3-9e65798ecd70 has links to several large downloads that combine into the complete install media
The release notes for SCVMM 2008 R2 SP1 cover several minor issues, you can obtain them at http://www.microsoft.com/downloads/en/details.aspx?FamilyID=14a0de11-cfa3-48d1-9dda-0a57b3408aa2&displaylang=en
Integration of SCVMM 2008 R2 SP1 with SCOM 2007 R2
There is no change from SCVMM 2008 R2 and SP1 in terms of the integration experience. Run the SCVMM 2008 R2 SP1 setup, Operations Manager integration portion, just like a new install. The SP1 integrated installer detects the upgrade environment and imports the updated SCVMM management packs.
The SCVMM 2008 R2 management packs are updated to version 2.0.4521.0, although the console views don’t expose any new Dynamic Memory features. For example, the Total RAM value in the SCVMM Virtual Machine view will always list the startup memory assigned to the VM and ignore any other Dynamic Memory related-values. (Also, for VMs with Dynamic Memory, the web-based SCVMM 2008 R2 SP1 self-service portal only displays the amount of memory assigned for startup memory.)
Tip: After performing SCVMM to SCOM integration, remember to enable PRO Tip generation in the SCVMM console at Administration -> General -> PRO Settings, as well as at the Host Group level in SCVMM. Failure to enable PRO tips in both places will prevent receipt of those PRO notifications!