3 Ways To Deal With Lingering Hyper-V Checkpoints Formerly Known as Snapshots

Lingering or phantom Hyper-V checkpoints or snapshots

Once in a while the merging of checkpoints, previously known as snapshots, in Hyper-V goes south. An example of this is when checkpoints are not cleaned up and the most recent avhdx or multiple of these remains in use as active virtual disk/still even as you don’t see them anymore as existing in the Hyper-V Manager UI for example. When that happens you can try looking at the situation via PowerShell to see if that show the same situation. Whatever the cause, once in while I come across virtual machines that have one or more avhdx (or avdh) active that aren’t supposed to be there anymore. In that case you have to do some manual housekeeping.

Now please, do not that in Windows Server 2012(R2) Hyper-V replica is using checkpoints and since Windows Server 2012 R2 backups also rely on this. Just because you see a snapshot you didn’t create intentionally, don’t automatically think they’re all phantoms. They might exits temporarily for good reason Winking smile. We’re talking about dealing with real lingering checkpoints.


Housekeeping comes in a couple of variants form simply dusting of to industrial cleaning. Beware of the fact that the latter should never be a considered a routine operation. It’s not a normal situation. It’s a last ditch resort and perhaps you want to call support to make sure that you didn’t miss anything else.

Basically you have tree options. In order of the easiest & safest to do first these are:

  1. Create a new checkpoint and delete it. Often that process will take care of merging the other (older) lingering avhd/avhdx files as well. This is the easiest way to deal with it and it’s as safe as it gets. Hyper-V cleans up for you, you just had to give it a kick start so to speak.
  2. Shut down the VM and create a new checkpoint. Export that newly created checkpoint. Yes you can do that. This will create a nicely exported virtual machine that only has the relevant vhd/vhdx files and no more checkpoints (avhd/avhdx). Do note that this vhd/vhdx is dynamically expanding one. If that is not to your liking you’ll need to convert it to fixed. But other than that you can dump the old VM (don’t delete everything yet) and replace it by importing the one you just exported. For added security you could first copy the files for save guarding before you attempt this. image
  3. Do manual mergers. This is a more risky process & prone to mistakes. So please do this only on a copy of the files. That way you’ll give Microsoft Support Services a fighting change if things don’t work out or you make a mistake. Also note that in this case you get one or more final VHDX files which you’ll use to create a new virtual machine with to boot from. It’s very hands on.

So that’s the preferred order of things to try/do in regards to safety. The 3rd option, is the last resort. Don’t do it before you’ve tried options 1 and 2. And as said above, if you do need to go for option 3, do it on copies.If you’re unsure on how to proceed with any of this, get an expert involved.

There’s actually another option which is very save but not native to Hyper-V. In the running virtual machine which current state you want to preserve do a V2V using Disk2vhd v2.01. Easy and sort of idiot proof if such a thing exists.

In a next blog post I’ll walk you through the procedure for the 3rd option. So if this is your last resort you can have practiced it before you have to use it in anger. Bit please, if needed, and do make sure it’s really needed as discussed above, try 1 first. If that doesn’t do it. Then try option 2. If that also fails try option 3. Do not that for option 2 and 3 you will have to create a new virtual machine with the resulting VHDX, having the required settings documented will help in this case.


Virtualizing Intensive Workloads on Hyper-V, Can It Be Done?

Can it be done?

All I can say is that, yes, absolutely, you can virtualize resource intensive workloads. Done right you’ll gain all benefits associated with virtualization and you won’t lose your performance & scalability.

Now I have to stress done right. There are a couple of major causes of problems with virtualization. So let’s look at those and see how a few well placed torpedoes can sink your project fast & effective.

Common Sense

One of them is the lack of common sense. If you currently have 10 SQL Servers with 12 15K RPM SAS Disks in RAID 1 and RAID 10 for the OS, TempDB, Logs & Data files, 64 GB of Memory, dual Quad Core sockets and teamed 1Gbps for resilience and throughput and you want to virtualize them you should expect to deliver the same resources to the virtualized servers. It’s technology people. Hoping that a hypervisor will magically create resources out of thin air is setting yourself up for failure. You cannot imagine how often people use cheap controllers, less disk or slower disks, less bandwidth or CPU cycles and then dump their workload on it. Dynamic memory, NUMA awareness, Storage QoS, etc. cannot rescue a undersized, ill conceived solution. I realize you have read that most physical servers are sitting there idle and let their resources go to waste. If you don’t measure this you can get bitten. You can get ripped to pieces when you’re dealing with virtualizing intensive workloads on Hyper-V based on assumptions.


Consider the entire stack

The second torpedo is not understanding the technology stack. The integration part of things or the holistic approach in management consulting speak. The times one could think as a storage admin, network admin, server admin, virtualization admin, SQL DBA, Exchange Engineer is long gone. Really, long gone. You need to think about the entire stack. Know your bottle necks, SPOF, weaknesses, capabilities and how these interact. If you’re still on premise for 100% that means you have to be a datacenter admin, not forgetting you might have multiple of those. And you’d better communicate a bit through DevOps to make sure the developers know that all those resources are not magically super redundant, are not continuously available without any limitation and that these do not have infinite scalability.



Drivers, firmware & bugs can sink your project

Hardware, VAR & ISV support is also a frequent cause of problems. They’ll al tell you that everything is supported. You can learn very fast and very painfully that this is too often not the case or serious bugs are wreaking havoc on your beautiful design. So I live by one of my mantras: “Trust but verify”. However sad it may be, you cannot in good faith trust OEM, VAR and ISVs. I’m not saying they are willfully doing this, but their experience, knowledge isn’t perfect & complete either. You have to do your due diligence. There are too many large scale examples of this right now with Emulex NIC issues around DVMQ. This is a prime example of how you slow acknowledgement of a real issue can ruin your virtualization project for intensive workloads and has been doing so for 9 months and might very well take a year to resolve. Due diligence could have saved you here. A VAR should protect its customers from that, but in reality they often find out when it’s too late. Another example is bugs in storage vendors implementation of ODX causing corruption or extremely slow support for a new version of Windows effectively blocking the use of it in production when you need it for the performance & scalability. I have long learned that losing customers and as such revenue is the only real language vendors understand. So do not be afraid to make hard decisions when you need to.


Knowledge & Due Diligence

Know your hypervisor and core technologies well. Don’t think it’s the same a hardware based deployments, don’t think all options and features work everywhere for everything, don’t think all hypervisor work the same. They do not. Know about Exchange and the rules/limits around virtualization. The same goes for SQL Server and any resource intensive workload you virtualize. Don’t think that the same rules apply to all workloads. There is no substitute for knowledge, experience and hands on testing, the verification part of trust but verify, remember? It goes for you as well!


It can be done

Yes, we can Winking smile! If you want to see some high level examples to simulate your appetite just browse my blog. Here are some pointers to get you started.




Live migration at the speed of light

Remember , don’t just say “Damn those torpedoes, full speed ahead” but figure out why, where, when and how you’ll get the job done.

TechEd North America 2014 Session

There is something extremely rewarding about seeing your name on the intro slide of a TechEd USA presentation. I helped deliver What’s New in Windows Server 2012 R2 Hyper-V together with Ben Armstrong yesterday and it was quite the experience.



A big thank you to Ben and Microsoft for the confidence they have shown in me and the opportunity to do this. A mention to our CEO who has the ability to look beyond the daily needs and facilitates his and encourages his employees to get out of the village to learn, grow and prosper. This is the principle one of my high school teachers lived and worked by, help people be all they can be.

The IT community around the Microsoft ecosystem is both a local and a global one. In this day and age knowledge gets shared and flows freely. People work with people and with organizations. No one gets anywhere in isolation.I’m happy to see so may of my buddies do so well. It’s great to see people succeed, grow, enjoy their work and reap the fruits of their efforts. Look at Benedict Berger who was presenting in the room next to ours or Aidan Finn, a long time community member and experienced speaker who won speaker idol and by doing so secured a speaker slot for next year. This has many reasons and one of them is people believing in you and giving you the chance to grab opportunities. To those I say, thank you very much!

Attending And Presenting at TechEd North America 2014

As you might well know I’m attending TechEd North America right now. I blogged about that. But I have to correct this a bit. Today I will also be presenting together with Ben Armstrong and help him deliver session DCIM-B380 What’s New in Windows Server 2012 R2 Hyper-V.

Ben Armstrong, Principal Program Manager on the Hyper-V team, will be showing you the wealth of features that provide capability, scalability, performance, availability and reliability in Windows 2012 R2 Hyper-V that make it THE capable and scalable cloud OS.

I’m honored to be able to show case a few of the technologies in Windows 2012 R2 we are leveraging in production today. So can you, really!


FREE WHITE PAPER: Configuring a VEEAM Off Host Backup Proxy Server for backing up a Windows Server 2012 R2 Hyper-V cluster with a DELL Compellent SAN (Fiber Channel)

Whilst I’m attending TechEd North America 2014, being able to learn and network again with the community at large I think this is a good moment to share. So here’s a little contribution to that community: it’s a white paper on How to configure a VEEAM Off Host Backup Proxy server for backing up a Windows Server 2012 R2 Hyper-V cluster with a DELL Compellent SAN (Fiber Channel).

VEEAM Back & Replication is currently under and extensive test before we make the decision. So far it is going (very) well. And no, VEEAM or DELL did not sponsor this. It’s sharing with the community. A prosperous, successful community makes my professional live better to!

I have to applaud VEEAM for allowing such easy access to their software for trials, to their engineers for assistance and to their support forum and resources even without yet being a paying customer. This is how it should be: vendors having faith in their products both in quality and ease of use. It’s a refreshing experience as some vendors don’t want you to get your hands on new versions of their products even as a existing paying customer “because due to its complexity we might get the wrong impression”. It’s even near impossible with some to get a test license for the lab of the version you currently use with some of them. Not so with VEEAM and that’s great.

I hope you enjoy it. As you might realize I don’t have this kind of infrastructure in my home lab so some of the screenshots have been edited / blurred. I’m sure you can live with that. Otherwise feel free to provide me with the gear in a paid for data center.

The Hyper V Amigos Showcast Episode 3: Live Migration

Here’s the 3rd episode of the Hyper-V Amigos show cast. As Carsten was overwhelmed with work (running your own business is very hard work) and had some issues with his storage spaces lab due to testing we’re discussing live migration optimizations in this installment.

 Carsten Rachfahl and I had a lot of fun again, even during the second take, yes we needed one. Apparently these software thingies require me to click on “record” Smile as there is no intelligent agent yet to act on my intention.

Carsten & I discussing & showing some live migration optimizations


I have written many blog posts on this subject already and I’m sure I’ll write more. Optimizing the use of the hypervisor (Hyper-V) across the entire storage, compute/memory & networking stack is one of my specialties and I enjoy this part of my job very much. I also like to share this information as real.

I’m sure you’ll agree that Hyper-V has come a long way in short period of time and I’m pretty sure we’re going to see Microsoft continue this pace for quite a while.

I have a blog post coming out (it’s in the queue) on my 4 top recommendations for optimal live migrations but here’s a search of relevant blog posts on this topic, and we referred to some of them during our show cast:


When you’re done reading al these posts on live migration you’ll have earned a nice refreshing beverage of your choice Mug.

One more thing, if you like these show casts let us know! Last but not least, I’m doing a demo heavy (only) session at ITProceed on June 12th 2014. Many local experts, community members  and I will be around afterwards to discuss these technologies.

Windows XP Clients Cannot Execute Logon Scripts against a Windows Server 2012 R2 Domain Controller – Workaround

The issue

The real issue is that you are still running Windows XP. The secondary issue is that you have Windows XP clients that cannot connect to a file share (NETLOGON) on a Windows Server 2012 R2 Domain Controller. If you try manually via \\domaincontroller\Netlogon it will throw an error like  "The specified network name is no longer available".  Security wise & moral pressure wise I kind of think this drives home the message you need to get off Windows XP. But I realize you’re in a pickle so here’s the workaround/fix.

Root Cause & Fix

Windows XP talks SMB 1.0 and that’s it. If this is not offered by the server (file server or domain controller) we have a problem. Now if you installed new Windows Server 2012 R2 servers they do not deploy the SMB 1.0 feature by default. If you upgraded from Windows 2008 R2 (perhaps even over Windows 2012) to get to Windows 2008 (R2) this feature kept in place. Other wise you’ll need to make sure SMB 1.0 is installed, it often (always?) is. Just check.


However there is a big change between Windows Server 2008 R2/Windows 2012. The LanmanServer service has a dependency set to SMB 2.0 and no longer to SMB 1.0

This is what it looks like on a Windows Server 2012 (or lower) domain controller:


This is what it look like on a Windows Server 2012 domain controller


So we need to change that on Windows 2012 R2 to support Windows XP. We can do this in the registry. Navigate to


  1. Change SamSS Srv2 to SamSS Srvimage
  2. Restart the Server (Lanmanserver) service (it will restart the dependent services like netlogon, DFS Namespace, .. as well)

You’re XP clients should be able to authenticate again. You can test this by navigating to \\domaincontroller\Netlogon on a XP client. This should succeed again.

If you have issues with Windows Server 2012 R2 file servers … this is also valid. When you do get rid of Windows XP. Go back to the original settings please Smile.

If you want to read more on SMB read this blog Windows Server 2012 R2: Which version of the SMB protocol (SMB 1.0, SMB 2.0, SMB 2.1, SMB 3.0 or SMB 3.02) are you using? by Jose Barreto (File Server team at Microsoft)

Finally, get off XP!

I think I said it enough on twitter and my blog Legacy Apps Preventing Your Move From Windows XP to Windows 8.1? Are you worried about HeartBleed? Good! Are you worried about still being on XP? No? Well dump SSL and use clear text authentication as XP is a free fire zone  anyway (as of April 8th 2014) and it’s just a matter of time before you’re road kill. Any company who has CIO/CTO/IT managers and other well paid functions and have let their organization be held hostage on XP (I’m not talking about a few PCs or VMs left and right) by legacy apps & ISV should realize they are the one who let this happen. Your watch. Your responsibility. No excuses.