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Posts tagged Hyper-V R2
If you install Windows Server 2008 R2 with Hyper-V, the pagefile will be automatically managed, which usually has a 1:1 ratio with physical memory. However VM’s use their own pagefile and do not use the host paging mechanism. If you have lots of memory, chances are your pagefile will be way too big.
If we compare two servers with 16GB of memory each, one installed with Hyper-V R2 and the other installed with Windows Server 2012 Hyper-V we clearly see different numbers. Both servers have run for several days.
In the figure to the left you will see that Windows has 16GB allocated but recommends 24GB (1:1,5)
In the figure to the right you see that Windows Server 2012 is much more intelligent and allocates considerably less memory for paging. It is fairly consistent with the best practice in R2 to set a fixed maximum for the pagefile between 4 and 6GB.
Although I haven’t found any best practices yet for the pagefile in Windows Server 2012 Hyper-V, this might suggest that you can use the autopilot for virtual memory in the latest server edition of Windows. Of course we need a little bit more experience in the field to really call this a best practice.
If you are looking for a very thorough blog on pagefile settings in R2, please visit this blog.
Here is another one on technet:
And finally a post about the Hyper-V Dynamic Memory and Host Memory Setting in R2:
Host Memory Reserve
The Host Memory Reserve, which reserves memory for the processes in the parent partition can be found in the following registry key:
Registry Key: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Virtualization
Value Name: MemoryReserve
Value Type: REG_DWORD
According to this post, the Host Memory in R2 is calculated in MB as follows: 384MB + (Memory in GB * 64)
So a 16GB host in R2 will have a default Host Memory Reserve of 384MB + (16 * 64) = 1.408MB
In two 16GB Windows Server 2012 hosts I looked at, the default Memory Reserve was 2048MB. We have to conclude that the formula used for Hyper-V R2 does not apply to Windows Server 2012.
I also looked at a Windows Server 2012 Hyper-V host with only 4GB which had a currently allocated pagefile size of 704MB and a recommended pagefile size of 3.582MB. This small host did not have a Host MemoryReserve entry at all, probably because a default 2GB Memory Reserve would be disproportional to the physical memory.
I had an interesting discussion about MemoryReserve with Michel Luescher who works for Microsoft Consultancy Services at Microsoft Schweiz. Michel is writing the chapters in Windows Server 2012 Hyper-V Installation and Configuration which deal with this subject.
IMPORTANT NOTE: Do not manually configure the Host MemoryReserve entry and leave this to Windows Server 2012 which will auto-configure this value on an as needed basis
In fact any newly installed Windows Server 2012 server with the Hyper-V role does not have a Host MemoryReserve entry in the registry and we still need to figure out under what circumstances this entry is added to the registry.
Take a look at Michel’s blog (German) on the subject:
There haven’t been any new blogs on Hyper-V.nu in the past weeks because of …. you know … an absolute dearth of time. It so happened that my other Hyper-V.nu colleagues had the same luxury problem in these economical challenging times.
So while I was doing a lot of other things which I will soon be able to talk about, I asked my colleague Sander Klaassen to fill in the gap and write a guest blog. Sander is also a Microsoft virtualization enthusiast and combines this with his broad other expertise.
Please welcome our guest blogger Sander Klaassen!
Over de last years I developed a script to quickly scan a customer’s IT environment. Recently I added a Hyper-V module which collects data from Hyper-V hosts and VM’s. I showed Hans Vredevoort the output and he asked me to write a blog about it. I was not sure to share the code, because it isn’t very clean, since I only occasionally work on it.
I created a VBScript and not a PowerShell script because I wanted to be able to run it without installing anything, and VBScript is part of windows since Windows 2000 so it’s always available.
This is also the reason why I made this script besides the regular Microsoft scan tools like ACT and MAP. They all need installation of components or even agents.
I modified the script for this blog, I changed the script by requesting input in a text file instead of Active Directory. This text file is a simple list of machine names:
Save it in the same directory as the VBScript with the name “machinelist.txt”
The script queries WMI name spaces of each machine and when it finds the Hyper-V role, it collects the following information:
UPDATE October 20th 2011: Here is a link to the video: http://t.co/v1xAMV6x
On Tuesday, October 4th Technical Evangelists Symon Perriman and Rick Claus are hosting an online conference on Virtualization Career Training with Microsoft Learning. This half day virtual event (8am – 11am PST) will offer a Level 100 to 200 introduction for anyone who wants to learn more about Microsoft Virtualization and how it can help their career. It is free and public so sign up for this warm-up for the Jump Start event on October 6th.
Module 1 – Technology: Learn about Microsoft’s virtualization technologies, how they work, and the future roadmap to the Cloud!
Module 2 – Career: Understand the importance of virtualization and Private Cloud, and how it can make or break an IT Professional’s career!
Module 3 – Certification: Get prepared for your next steps towards a virtualization career by understanding and preparing for the Microsoft 70-659 Technical Specialist exam, Windows Server 2008 R2, Server Virtualization.
Update October 21st, 2011 (see bottom)
Let’s assume the following scenario:
- You have a Hyper-V R2 SP1 cluster that has three or more nodes
- You are using Cluster Shared Volumes
- You learnt about the Cluster Validation problem that was solved by KB2531907 back in May 2011, which prevented the “Failed to get SCSI page 83h VPD descriptors for cluster disk <number> from node <node name> status 2” error after running the Validate SCSI Vital Product Data. It also solved the “Disk with identifier <value> has a Persistent Reservation on it. The disk might be part of some other cluster. Removing the disk from validation set” error when running the List Potential Cluster Disks test. The hotfix resolves an issue in which the storage test incorrectly runs on disks that are online and not in the Available Storage group. The problem can also be caused by other issues such as storage problems or an incorrect configuration which means you have to check your storage configuration and check related events on your Hyper-V hosts.
- You want to add more capacity and add a new Hyper-V host.
When you look at the Hyper-V marketing page, you’ll notice that the list of supported operating systems is incomplete. If you want to know the whole support story including the recent CentOS Linux distribution that was added please go to the TechNet page, which also states end-of-support for some older Microsoft operating systems such as Windows Server 2000 with SP4 and Windows XP with SP2.
Here is the list for Linux distributions and as you can see they all have multi processor support up to the current maximum of Hyper-V R2.
For more details go to http://technet.microsoft.com/en-us/library/cc794868(WS.10).aspx
Today I had to deliver a few 500GB Fixed Sized VHD’s in our Nobel Hyper-V Cloud Datacenter. The job had to be finished in a few hours involving provisioning the LUN, presenting them to the hosts, creating the VHD, adding the VHD to the Virtual Machines and prepare/format the disks for final use within the VM. Of course this had to be done without downtime to the users. Another very easy job but let me warn you: “It takes a bit of time!”
The VM’s involved were two Exchange 2010 DAG servers, the one in our Hilversum datacenter on an HP BL460G6 blade server connected to HP EVA enterprise grade storage with dozens of FC 450GB 15K disks and the other in the customer’s datacenter in Amsterdam, which serves as a DR site. The DR site has no HP EVA storage and there is no replication. We use a few single Hyper-V ProLiant ML370 servers with a bunch of local 1TB FATA storage. We backup to a local DPM2010 server in Hilversum and replicate that to a second DPM2010 server in Amsterdam. So recovery can be relatively fast.
How about speed?
Creating a 500GB fixed sized VHD on the EVA storage took only 49 minutes or almost 10 times faster.
Creating a 500GB fixed sized VHD on the Direct Attached Storage (DAS) on the recovery Hyper-V Server where the DR instance of the Exchange 2010 VM lived took a little over 8 hours.
Of course this is not a problem but very costly if the customer has to pay by the hour.
I was happy to have started the fixed disk creation the evening before so when I looked this morning both VM’s were ready and waiting to be used.
Recently I was asked to describe the correct procedure for defragmenting Cluster Shared Volumes on a Hyper-V R2 cluster. This is not really a very complicated task but if you have never had the opportunity to give it a try, this blog post will offer you the exact steps using PowerShell.
Let’s start with a case description: the System Center Operations Manager Windows Management Pack is reporting “Logical Disk Fragmentation Level is high” for your Hyper-V R2 servers.
A Cluster Shared Volume (CSV) contains the configuration, virtual hard disk and snapshot files of multiple Hyper-V guests. Notably fragmentation of the large VHD files deserve your attention.
Fragmentation of these files can become a problem because the disk head needs to use an increasing number of seeks, lowering the throughput and thus the perceived performance of the guest as a whole.
On the other hand, NTFS has become more and more efficient in recent OS versions and fragmentation need not always have a severe impact on performance.
CSV is a distributed orchestration layer on top of NTFS (implemented as a file system filter driver) and for fragmentation it takes advantage of all the NTFS techniques. The advantage of this design is that all disk management tools which have been written for NTFS continue to work, including a variety of defrag tools.
I can recommend a series that is currently being written on Hyper-V Networking Optimizations by the hand of Cristian Edwards who is Premier Field Engineer in Microsoft Virtualization at Microsoft.
Since Hyper-V R2 network optimizations were not only supported at the host level but also in the guest. If you roam the Internet you will see a lot of talk and confusion about whether to configure things like TCP Chimney Offload or when and how to configure Virtual Machine Queues (VMQ), Receive Side Scaling (RSS) and Jumbo Frames.
I am very glad I found this great source and we might consider this the definitive guide to configuring the Hyper-V networking optimizations.
Today at TechEd 2011 in Atlanta we learnt that Microsoft now officially supports CentOS. CentOS is a popular free Linux distribution and is among the top three most popular ones.
CentOS has been added to the list of formally supported Linux Distributions. The others are SUSE Linux Enterprise (v10 and v11) and Red Hat Enterprise Linux 5.2 and up. With the added support for CentOS, Windows Virtualization becomes even a better candidate for mixed Windows-Linux environments.
Many other Linux distributions can be easily integrated into a Hyper-V R2 environment since Microsoft submitted the code for the Hyper-V integration components. These additions enable native Hyper-V support for synthetic devices (video, network, mouse), multi-processor support and graceful shutdown of Linux VM’s.
In this blogpost Ben Armstrong explains how to install Ubuntu Server 10.10 on Hyper-V.
Another nice announcement was made by Yusuf Öztürk from Istanbul who developed a PowerShell based new functionality for Linux virtual machines on Hyper-V: Set-LinuxVM
What you can do with Set-LinuxVM?
- Unattended IP, Hostname and DNS configuration for Linux VMs
- Automatic Linux integration components installation
- Multi Distro Support: Debian, Ubuntu, Centos, Fedora, Redhat and Suse
- Automatic CPanel installation for Redhat and Centos
- Linux VM Template support (Use Skip for EnableLIC switch
- Hyper-V support! You don’t need SCVMM to use this script.
- Multiple Hyper-V and SCVMM host support.
- Automatic Emulated NIC to Synthetic NIC support
- No need to internet connection (SSH access etc.) or additional changes on VM.
- Custom Answer File support! You can execute your own scripts.
Because I don’t want to copy Michel de Rooij’s blog I will simply make a reference to his blog. Many of us know that the Unified Messaging role was not supported for Virtualization and that the Exchange 2010 Mailbox Role if used in Database Availability Groups was not supported if implemented on top of Hyper-V, VMware or XenServer host failover clustering. So in a Hyper-V environment we were unable to use Live Migration (although I know many who went against that policy).
With the release of a new whitepaper on virtualizing Exchange this now seems to have changed. Michel explains further in his blog.