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Posts tagged Windows Server 2008 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:
In the past week I attended TEC Europe 2011 in Frankfurt and presented a Hyper-V Storage Deep Dive session for a small but highly specialized audience. TEC2011 is certainly not known for its sheer size but because of its small size it is very easy to get into touch with both other speakers and visitors. My Hyper-V.nu and inovativ colleague Jaap Wesselius was also present and he presented for the third consecutive year. So that must mean something. Jaap presented a number of topics around Exchange, Hyper-V and instructed an Exchange 2010 Availability workshop.
My presentation was part of the Cloud and Virtualization track. This track was a mixture of private cloud management, server virtualization, application virtualization, desktop virtualization, identity, software as a service, infrastructure as a service, PowerShell, etc. I really enjoyed the depth of most presentations and talking to a good number of friends I normally only meet on the social media platforms.
My presentation dived into 10 storage topics related to Hyper-V which were analyzed on both their strengths and weaknesses and compared to what will be available in Hyper-V version 3 in Windows Server 8.
Hyper-V Virtual Disks
Hyper-V Shared Disks
Cluster Shared Volumes
Hyper-V Data Protection
Cluster Storage Validation
Storage Configuration with PowerShell
You can download the PowerPoint including some of the PowerShell 3 scripts I used for configuring in a Windows
Server 8 Hyper-V and File Server Cluster: http://bit.ly/qeO2Z3
Left to right: @hvredevoort @jaapwess @workinghardinit @hypervserver @rickslager
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.
When you install Windows Server 2008 R2 the default page file setting is ‘Automatically manage paging file size for all drives’. Hyper-V hosts are often loaded with a lot of RAM (96GB is not an exception). Because of the ‘Automatically manage paging file size for all drives’ setting your page file will be huge:
This post is updated after co-blogger Hans Vredevoort contacted some of the storage folks in Microsoft to discuss the MPIO/cluster member initiators issue. It turns out that order list number 3 is not correct.
As a follow-up after releasing the Microsoft iSCSI Software Target 3.3 Microsoft has released an support article specifing the limits.
This topic provides the supported and tested Microsoft iSCSI Software Target 3.3
limits. The following tables display the tested limits and the enforced limits
where applicable.In addition, the following limits apply:
- You should not use network adapter teaming with Microsoft iSCSI Software
Target 3.3 for iSCSI communication.
- If you plan to use multiple network adapters for iSCSI communication, you
should separate them into their own subnets, set up virtual IP addresses, and
then implement MPIO.
- MPIO is
notsupported for iSCSI initiators when used in conjunction with
Microsoft iSCSI Software Target if the initiators are part of a failover
A couple of years ago Microsoft acquired a company called “String Bean Software” which was IMHO a simple but great iSCSI Target solution, and it it was incorporated into the StorageServer product.
Today Microsoft launched the iSCSI Software target 3.3 for public download. This is absolutely great, now we have the possibility to create (Hyper-V) clusters on shared storage!
More info on the Jose Barrato’s Blog and it can be downloaded from the Microsoft download site: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=45105d7f-8c6c-4666-a305-c8189062a0d0
This begins to look like a serial story. Hyper-V and NIC Teaming. Ever since I wrote a blog on using native VLANs with HP NIC Teaming and Hyper-V, I have been reluctant to try new versions. Now that Windows Server 2008 R2 SP1 was published almost a month ago, I have attempted to evaluate the consequences for this lovely combination.
Let me begin with referring to my blogs on NIC Teaming:
As from HP Network Configuration Utility (NCU) 10.10.0.x it is possible to use native VLANs in combination with Hyper-V without going through the hassle of manually adding multiple VLANs on the team and creating Hyper-V virtual networks and string those two together. By using a team setting called Promiscuous Mode we only had to make sure VLANs were known on the trunk and we were able to apply a VLAN ID to the virtual network adapter in the Hyper-V guest.
I have tested a couple of combinations:
TESTED CONFIGURATION 1
Config: Windows Server 2008 R2 SP1 with NCU 10.10.0.0 and Broadcom 5.2.22.x drivers from HP PSP 8.60 but without teaming configured. VLAN configured on adapter itself.
Result: Guest can communicate with network. VLANs are passed through correctly.
Conclusion: Although you have no network redundancy in this configuration, it is easy to add a VLAN id to the vNIC in the guest. Promiscuous mode is not applicable here.
TESTED CONFIGURATION 2
It is not uncommon that hardware vendors have to fix their array controller firmware. In this case it is HP’s P2000 G3 firmware for the FC/iSCSI combined models. Again it is a fix for problems as a result of customers using bigger clusters. Here we have a problem with Windows Server 2008 R2 clusters which surfaces with bigger clusters, long IQN names and a maximum of the space available for SCSI-3 reservations. Haven’t we seen this kind of trouble before. I can assure you that admins of Hyper-V R2 clusters surpassing these limits weren’t all that happy.
Using a long IQN name for iSCSI initiators may lead to issues while using SCSI-3 reservations and Persistent Group Reservations, particularly when trying to create large clusters with multiple paths to each LUN. A predefined area is used to store SCSI-3 reservation keys for each initiator path to each LUN and, when a large number of IQN entries are attempted to be stored, the array can run out of space in this area. This issue is dependent on the number of nodes and the number of paths per node accessing individual LUNs. This issue has been seen during the cluster validation process on Windows 2008 R2 clusters with 16 nodes, where each node had 4 paths to each LUN of the array.
One of my colleagues noticed rather strange behavior with one of the Windows Server 2008 R2 servers which is part of a 7-node Hyper-V cluster built with HP BL460c G6 blade servers. This behavior showed up during host level backups of Hyper-V virtual machines.
What problems were observed?
The System Reserved Partition did not have a label and was offline after a reboot
A CSV could be offline if it was owned by this particular cluster node
These problems could be temporarily solved by assigning a drive letter. Oddly enough Disk Manager and Diskpart did not agree with each other about the disk being online or offline. In Diskpart the problematic partition would show offline and in Disk Manager it was online. It would show offline if the disk had no label:
With a disk label:
Host level (external) backups of Hyper-V child partitions failed (while internal backups of VM’s with a backup agents would succeed)
During this external backup multiple VHD’s are created but apparently nothing is written to it.
Ultimately the Hyper-V VSS writer faults with a non-tryable error. However, if we move the VM to another host, the backup completes successfully.
Multiple attempts to solve this problem were made:
Evict node from cluster and rejoin cluster
Remove backup agent (DPM2010) and add it again
Remove Server Backup feature and add it again
Remove DPM2010 Protection Group and recreate it
Backup with and without label on reserved partition
So far the only option left was to reinstall the server.
Just by coincidence I found a recent KB article called “System Partition goes offline on Windows Server 2008 and Windows Server 2008 R2 after installing some 3rd Party Disk or Storage Management Software” dated September 29, 2010: http://support.microsoft.com/kb/2419286/
This article names three issues:
Hyper-V Role Cannot be Installed “Failure configuring Windows features”
“Failed to prepare storage for testing on node 1 status 87” during Cluster Validation
“The boot configuration data store could not be opened. The system cannot find the file specified.
In our case it was issue 2 that troubled us.
The resolution was to online the System Reserved Partition:
Select volume n (n= the 100MB system partition)
Or from Disk Management:
Select the 100MB volume and Right-Click it
Change drive letter & path
Assign a drive letter
This is something we had already found out. The bad thing is that it returns after a reboot.
We checked the following:
No 3rd party disk or storage management software is installed
No anti-virus software is installed on the cluster node
Update: October 6, 2010
Talking to several people in my network we’ve come up with the following (partial and possibly full) solutions:
Assign a drive letter, and leave it during a reboot: result was that system partition kept online, but the host level backup of guest partitions with DPM 2010 failed (this idea was presented by several people, a.o. Kurt Roggen and an engineer at Microsoft)
Run a chkdsk /r on the system drive (part of solution) and run the system readiness tool which replaces the corrupt mum files from a fully functional Hyper-V host to the one that was having issues:
http://support.microsoft.com/kb/947821 (this tip was presented by Annur Sumar)
Unfortunately we were pressured to get the host running again so we just reinstalled it. That is solution #3 and although not very efficient, one that works in almost all situations
So thanks for the great feedback to all that contributed!