Month: January 2014

KB2902821 – A VM On WS2012 Or WS2012 R2 Hyper-V Cannot Use DLC Protocol To Contact SNA Host

This is an odd KB article from Microsoft for Hyper-V. It deals with a virtual machine that is running on on Hyper-V Server 2012 or Hyper-V Server 2012 R2.  The VM is configured to use the DLC protocol but the VM cannot connect to an SNA host.

Symptoms

You use Microsoft Hyper-V Server 2012 or Microsoft Hyper-V Server 2012 R2 to host a virtual machine such as for Microsoft Host Integration Server 2009. If the virtual machine is configured to use the Data Link Control (DLC) protocol to connect to a Systems Network Architecture (SNA) host such as an IBM Mainframe z/OS system, the connection fails.

Cause

This problem occurs because Hyper-V Server 2012 and Hyper-V Server 2012 R2 do not support 802.3 frame types that do not have a Sub-Network Access Protocol (SNAP) header.

A hotfix is available from Microsoft to resolve this issue.

Hyper-V Virtual NUMA Versus Dynamic Memory

When you are using VMs with a large amount of memory then NUMA topology becomes important. Hyper-V can reveal the underlying physical NUMA topology to the VM so that the guest OS and NUMA-aware apps (such as SQL Server) efficiently assign memory and schedule processes to make the most of the boundaries.

There is something important to note. Enabling Dynamic Memory in the settings of a VM disables virtual NUMA. That means that the vast majority of VMs will not have virtual NUMA. To squeeze the best processor/memory performance out of larger VMs you will need to use static RAM, as noted here under Virtual NUMA:

Virtual NUMA and Dynamic Memory features cannot be used at the same time. A virtual machine that has Dynamic Memory enabled effectively has only one virtual NUMA node, and no NUMA topology is presented to the virtual machine regardless of the virtual NUMA settings.

So you have a balancing act to do:

  • Applications and large VMs that might benefit from virtual NUMA probably should have static memory. Enabling Dynamic Memory would indirectly reduce the potential performance of the services provided by that VM because virtual NUMA would be disabled.
  • Note that workloads that are not NUMA-aware cannot make use of virtual NUMA. Therefore enabling Dynamic Memory will not impact performance, and it makes sense to optimize the RAM assignment.
  • Maybe service performance isn’t a big deal (!?!?!?) but the cost of RAM is. Then you would always (if the app/guest OS support it) enable Dynamic Memory.

This is not ideal. Introducing a human decision into a cloud where uneducated “users” are deploying their own VMs makes things less efficient. Hopefully MSFT will overcome the Dynamic Memory versus virtual NUMA conflict in a future version, but when you think about it, this would difficult to do.

Event – Windows Server & System Center 2012 R2 Briefing For Partner Sales

MicroWarehouse are running a breakfast briefing for Microsoft partners in Dublin in a couple of weeks. I’ll be presenting on Windows Server 2012 R2, System Center 2012 R2, and some of the business features of Windows 8.1.  The intended audience is MICROSOFT PARTNERS ONLY:

  • Sales
  • Account managers
  • Technical pre-sales

We’re running the event twice, once in north Dublin and once in south Dublin, to accommodate scheduling conflicts.

Additional events in Belfast, Galway, and Cork will be announced soon, with probably with some additional content.

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Memory Page Combining

My reading of the Windows Server 2012 R2 (WS2012 R2) Performance and Tuning Guide continues and I’ve just read about a feature that I didn’t know about. Memory combining is a feature that was added in Windows 8 and Window Server 2012 (WS2012) to reduce memory consumption. There isn’t too much text on it, but I think memory combining stores a single instance of pages if:

  • The memory is pageable
  • The memory is private

Enabling page combining may reduce memory usage on servers which have a lot of private, pageable pages with identical contents. For example, servers running multiple instances of the same memory-intensive app, or a single app that works with highly repetitive data, might be good candidates to try page combining.

Bill Karagounis talked briefly about memory combining in the old Sinofsky Building Windows 8 blog (where it was easy to be lost in the frequent 10,000 word posts):

Memory combining is a technique in which Windows efficiently assesses the content of system RAM during normal activity and locates duplicate content across all system memory. Windows will then free up duplicates and keep a single copy. If the application tries to write to the memory in future, Windows will give it a private copy. All of this happens under the covers in the memory manager, with no impact on applications. This approach can liberate 10s to 100s of MBs of memory (depending on how many applications are running concurrently).

The feature therefore does not improve things for every server:

Here are some examples of server roles where page combining is unlikely to give much benefit:

  • File servers (most of the memory is consumed by file pages which are not private and therefore not combinable)
  • Microsoft SQL Servers that are configured to use AWE or large pages (most of the memory is private but non-pageable)

You can enable (memory) page combining using Enable-MMAgent and query the status using Get-MMAgent.

You’ll find that memory combining is enabled by default on Windows 8 and Windows 8.1.  That makes these OSs even more efficient for VDI workloads. It is disabled by default on servers – analyse your services to see if it will be appropriate.

There is a processor penalty for using memory combining. The feature is also not suitable for all workloads (see above).  So be careful with it.

KB2868279–Moving A VM From WS2012 R2 Hyper-V To WS2012 Hyper-V Is Not Supported

I have to admit that I find this KB article and support statement to be quite baffling.  It states that:

Moving a virtual machine (VM) from a Windows Server 2012 R2 Hyper-V host to a Windows Server 2012 Hyper-V host is not a supported scenario under any circumstances. 
When you try import a VM that is exported from a Windows Server 2012 R2 Hyper-V host into a Windows Server 2012 Hyper-V host, you receive the following error message: 

Hyper-V did not find virtual machines to import from the location <folder location>.
The operation failed with error code ‘32784’.

I am going to raise this with the product group. I see it as a genuine issue because anyone doing an upgrade-migration will require a rollback plan that will work and is supported.

You can move a VM from a Windows Server 2012 Hyper-V host to a Windows Server 2012 R2 Hyper-V host. This is a supported scenario and cane even be done with zero downtime using Cross-Version Live Migration.

Recommended Updates Lists For WS2012 R2 Hyper-, Failover Clustering & File Services

Microsoft has published pages that list the hotfixes that have been published for Windows Server 2012 R2 Hyper-V and Failover Clustering. You can find them here:

Make sure you wait a month before deploying (let someone else do the testing for you) and then use tools like Cluster Aware Updating (CAU) do the heavy lifting.

EDIT: I just added the link to the updates for file services. You’ll want those if implementing SMB 3.0 storage. You’ll find the updates for R2 on the bottom of the page (shared with WS2012).

How Much RAM & CPU Does Window Server Deduplication Optimization Require?

I’ve been asked about resource requirements for the dedupe optimization job before but I did not have the answer before now.

Processor

The CPU side is … not clear.  The dedupe subsystem will schedule one single-threaded job per volume. That means a machine with 8 logical processors is only 1/8th utilized if there is a single data volume. Microsoft says:

To achieve optimal throughput, consider configuring multiple deduplication volumes, up to the number of CPU cores on the file server.

That seems pretty dumb to me. “Go ahead and complicate volume management to optimize the dedupe processing”. Uhhhhh, no thanks.

Memory

Microsoft tells us that 1-2 GB RAM is used per 1 TB of data per volume.  They clarify this with an example:

Volume Volume size Memory used
Volume 1 1 TB 1-2 GB
Volume 2 1 TB 1-2 GB
Volume 3 2 TB 2-4 GB
Total for all volumes 1+1+2 * 1GB up to 2GB 4 – 8 GB RAM

By default a server will limit the RAM used by the optimization job to 50% of total RAM in the server.  So if the above server had just 4 GB RAM, then only 2 GB would be available for the optimization job.  You can manually override this:

Start-Dedupjob <volume> -Type Optmization  -Memory <50 to 80>

There is an additional note from Microsoft:

Machines where very large amount of data change between optimization job is expected may require even up to 3 GB of RAM per 1 TB of diskspace.

So you might see RAM become a bottleneck or increase pressure (in a VM with Dynamic Memory) if the optimization job hasn’t run in a while or if lots of data is dumped into a deduped volume.  Example: you have deployed lots of new personal (dedicated) VMs for new users on a deduped volume.

How Many SSDs Do I Need For Tiered Storage Spaces?

This is a good question.  The guidance I had been given was between 4-8 SSDs per JBOD tray.  I’ve just found guidance that is a bit more precise.  This is what Microsoft says:

When purchasing storage for a tiered deployment, we recommend the following number of SSDs in a completely full disk enclosure of different bay capacities in order to achieve optimal performance for a diverse set of workloads:

Disk enclosure slot count Simple space 2-way mirror space 3-way mirror space
12 bay 2 4 6
24 bay 2 4 6
60 bay 4 8 12
70 bay 4 8 12

Minimum number of SSDs Recommended for Different Resiliency Settings

2 Months + Christmas – How The Nokia Lumia 1020 Windows Phone Has Fared

I’ve been pleasantly surprised how well the Lumia 1020 has fared, reviewing it here and on the Petri IT Knowledgebase. How has the phone continued to work over time?

It’s not all been smooth sailing. There are times when there’s an app that I want to use that just is not there. I like to get my news with a sense of humour, and TheJournal.ie does sadly not have a Windows Phone app. That has me reaching for the browser or for my Lenovo Yoga 8 Android tablet where there is an app. I’ve also been doing some travel booking and there’s a distinct shortage of those apps on Windows Phone.

Over the holidays I did quite a bit of driving. And I like to drive safe, so I have a third-party Bluetooth hands free kit (Parrot CTK 3100) with recently upgraded firmware. Strictly speaking, the kit does not support the Lumia 1020, but it does support the 925 and 52x handsets. The experience was working well, but something went wrong over the holiday – I could make/answer calls but the audio failed to go over the kit. I did a little digging and eventually reset the phone. No joy. Then I “reset” the kit by removing all paired phones and that’s when I noticed something: My phone was registered twice, once under the default “Windows Phone” name and again with the unique name I had recently entered in the Windows Phone app. I made sure both entries were gone and I re-paired and tested. Everything was fine once again. Phew – I’d had to resort to using my HTC One for a couple of days so I could drive safely but now I am back on the Lumia 1020.

The real test for this phone was communications, especially on Christmas day. I was celebrating the day with family. My girlfriend was with her family and I have friends scattered all over. Windows Phone was designed from the ground up for social media integration. And that’s what I got … in one app. Facebook, LinkedIn, and Twitter are all added as accounts in the Windows Phone settings. That means I get integrated chat in the Messaging app, not just SMS texting. I was texting and Facebook IMing in one place on the phone. It worked really well, able to stay in contact, and I didn’t have to app switch.

There was some driving to be done too and Nokia’s Here Maps worked perfectly, even correcting me when I encountered a wrong road sign on New Years Eve!

The big feature (figuratively and literally) of the Lumia 1020 is the camera. Christmas means low light and the camera did get used. Microsoft got the physical reference interface of Windows Phone right: the dedicated camera button is so handy. I took photos in low light both with and without flash. Obviously the flash-less photos suffer with motion blur and/or camera shake and some grain, but what the Lumia produces beats what any compact camera might offer in the same circumstances, at least in my experience!

The other thing I’ve been doing is using the phone for music: be it while travelling or doing stuff around the house. The speaker quality is nowhere near what the HTC One offers (which might be best in class, including tablets) so I acquired a Creative (remember them!!!) portable Airwave HD Bluetooth/NFC speaker. Adding music to the phone is a breeze, and adding playlists from Windows Media Player is much easier than it is for Android. Tap the phone, pair, and music is playing via the speaker with volume control on the speaker and one the phone.  Nice!

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The Creative Airwave HD is available from:

So Windows Phone 8 on the Nokia Lumia 1020 has had a real world, real user test and it’s passed, although there are still questions remaining about app availability.

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KB2878635 – A December 2013 Update To Improve CSV Backup Resiliency On WS2012 Hyper-V

Microsoft released an update in December 2013 that that improves the resiliency of the cloud service provider in Windows Server 2012. That’s a little “marketing speak”. In truth, this update is designed to resolve issues with CSV backup on Windows Server 2012 Hyper-V. This update two fixes. Please note the post-installation instructions!!!!

Symptoms

This article introduces an update that improves the resiliency of the cloud service provider in Windows Server 2012. This update is dated December 2013.
This update replaces update 2870270, which is used to improve resiliency. Also, this update includes update 2869923 and update 2908415. Additionally, the update resolves several issues that occur in the following scenario: 

  • You have a Hyper-V failover cluster.
  • The Hyper-V resources are saved in .vhd files on Cluster Shared Volumes File System (CSVFS) volumes.
  • You use a backup solution. For example, you use System Center Data Protection Manager (DPM) in the Hyper-V environment.
  • You try to perform a backup, and a snapshot is taken of the CSVFS volume.
  • The current active node encounters an error, and the cluster fails over to another node.
  • DPM may start a consistency check on the volume unexpectedly.
Issue 1

Snapshots that are no longer being used are not cleaned up. Therefore, Volume Shadow Copy Service (VSS) snapshots may accumulate on Cluster Shared Volumes (CSV) and guest virtual machines. This causes a deadlock in the Resource Hosting Subsystem (RHS) process, and causes  CSV failures. Additionally, all Hyper-V instances that uses the VHD files go down.
Additionally, the following events are logged separately in the Cluster log and in the System log:

Software snapshot creation on Cluster Shared Volume(s) (‘volume location‘) with snapshot set id ‘snapshot id‘ failed with error ‘HrError(0x80042308)(2147754760)’. Please check the state of the CSV resources and the system events of the resource owner nodes.
Log Name: System
Source: Microsoft-Windows-FailoverClustering
Date: Date and time
Event ID: 5120
Task Category: Cluster Shared Volume
Level: Error
Keywords:
User: SYSTEM
Computer: Computer name
Description: Cluster Shared Volume ‘Volume1‘ (‘name’) is no longer available on this node because of ‘STATUS_IO_TIMEOUT(c00000b5)’. All I/O will temporarily be queued until a path to the volume is reestablished.

Log Name: System
Source: Microsoft-Windows-FailoverClustering
Date: Date and time
Event ID: 5142
Task Category: Cluster Shared Volume
Level: Error
Keywords:
User: SYSTEM
Computer: Computer name
Description: Cluster Shared Volume ‘Volume3‘ (‘Cluster Disk 4‘) is no longer accessible from this cluster node because of error ‘ERROR_TIMEOUT(1460)’. Please troubleshoot this node’s connectivity to the storage device and network connectivity.

Issue 2

If a CSVFS volume is repeatedly added and removed from a cluster, or if CSVFS snapshots are repeatedly created, the Plug and Play (PnP) hive in the following registry path may grow with many additional registry keys: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetEnumSTORAGEVolumeSnapshot.
Therefore, installation of PnP volumes (which occurs usually during a resource move or failure) may become slow.  This update prevents future unnecessary growth in the volume snapshot registry key, but does not clean up existing registry entries.

 

Resolution

A supported hotfix is available from Microsoft.

Post-Installation Instructions

After you install this hotfix on a Hyper-V server, you must update the integration components in the virtual machines that are running Windows Server 2012. To do this, use Hyper-V Manager to connect to the virtual machine. This starts the Virtual Machine Connection tool. Then, on the Action menu, click Insert Integration Services Setup Disk. Run the Setup.exe file on the Integration Services Setup disk to update the integration component.