The Hyper V Amigos Showcast Episode 6: Storage Spaces

Posted on October 23, 2014 by workinghardinit

Everybody is very busy and I’m a bit tires but here’s the 6th episode of the Hyper-V Amigos show cast. In this episode we get to play a bit with storage spaces in Carsten’s lab.

As always we had a lot of fun doing so and thanks to Carsten Rachfahl and the assistance of Kerstin (his charming wife, also an MVP, in Office 365) we could simulate hardware failures & film them for you!

Carsten & I discuss several scenarios and what’s happening during failovers. Carsten is assisting customers with this a lot so he has some of the most varied experience with storage spaces and SOFS out there! Interesting stuff and for people who haven’t even looked at Windows Server 2012 or later yet a wake up call to start as the world is not limited to what we once knew. It’s not your daddy’s Windows anymore Winking smile

I hope you enjoy it and we’re already planning for the next one!

Dell generation 13 servers & Intel E5 v3 18 core CPUs are upon us in world where per core licensing is reality

Posted on September 8, 2014 by workinghardinit

As I watched the Intel E5 v3 launch event & DELL releasing their next generation servers to the public to purchase there is a clear opportunity for hardware renewal next year. I’m contemplating on what the new Intel E5 v3 18 core processors

and the great DELL generation 13 PowerEdge Servers mean for the Hyper-V and SQL server environments under my care.

For the Hyper-V clusters I’m in heaven. At least for now as Windows is still licensed per socket at the time of writing. vNext has me worried a bit, thinking about what would happen if that changes to core based licensing to. Especially with SQL Server virtualization. I do hope that if MSFT ever goes for per core licensing for the OS they might consider giving us a break for dedicated SQL Server Hyper-V clusters.

For per core licensing with SQL Server Enterprise we need to run the numbers and be smart in how we approach this. Especially since you need Software Assurance to be able to have mobility & failover / high availability. All this at a time you’re told significant cost cutting has to happen all over the board.

So what does this mean? The demise of SQL Server in the Enterprise like some suggest. Nope. The direct competitors of SQL Server in that arena are even more expensive. The alternatives to SQL are just that, in certain scenarios you don’t need SQL (Server) or you can make due with SQL Server Express. But what about all the cases where you do really need it? You’ll just have to finance the cost of SQL Server. If that’s not possible the business case justifying the tool is no longer there, which is valid. As the saying goes, if you can’t afford it, you don’t need it. A bit harsh yes, I realize, but this is not a life saving medicine we’re talking about but a business tool. There might be another reason your SQL Server licensing has become unaffordable. You might be wasting money due to how SQL Server is deployed and used in your environment. To make sure you don’t overpay you need to evaluate if SQL Server consolidation is what is really needed to save the budget.

Now please realize that consolidation doesn’t mean stupidly under provisioning hardware & servers to make budget work out. That’s just plain silly. For some more information on this, please read Virtualizing Intensive Workloads on Hyper-V, Can It Be Done

So what is smart consolidation (not all specific to SQL Server by the way):

You have to avoid physical SQL Server sprawl with a vengeance.
You need to consolidate SQL Servers aggressively.
Virtualize on a dedicated SQL Server Hyper-V cluster if possible
Favor scale out over scale up in the Hyper-V scenario to keep node costs reasonable and allow for affordable expansion.
Use 2 socket servers and replace the hardware faster to keep the number of needed cores down.
- This allows to leverage modern commodity, high performance storage, networking and compute where you can in order to optimize workloads & minimize costs.
- It helps save on power consumption & cooling
- More nodes with lesser cores (scale out approach) reduces VM density per node but also keep the cost of adding a node (with SQL Server per core licensing, or when it comes to that for the OS as well), which is your scaling block with a fixed cost under control. It’s all about balance and it isn’t as easy as it seems.
Play the same game with storage. This can be a harder sale to make internally. Traditionally people hang on to storage longer due to the high CAPEX. I have said it before, storage vendors have to deliver more & better. Even the challengers & hyper converged systems are still too expensive to really get into a short renewal cycle for most organizations.

Be smart about it. A great DBA can make a difference here and some hard core performance tuning is what can save a serious amount of money. If on top of that you have some good storage & network skills around you can achieve a lot. Next to the fact that you’ll have to spend serious money for serious workloads the ugly truth is that consolidation requires you find your peak loads and scale for those with a vengeance. Look, maxing out one server on which one SQL Server is running isn’t that bad. But what if 3 SQL Servers running a peak performance spread over a 3 node Hyper-V cluster dedicated to SQL Server VMs might kill performance all over!

The good news is I have solid ideas,visions, plans and options to optimize both the on premise & cloud of part of networking, storage & compute. Remember that there is no one size fits all. Execution follows strategy. The potential for very performant, cost effective & capable solutions are right there. I cannot give you a custom solution for your needs in a blog post. One danger with fast release cycles is that it requires yearly OPEX end if they cannot guarantee it the shift in design to solutions with less longevity could become problematic if they can’t come up with the money. Cutting some of the “fat” means you will not be able to handle longer periods of budget drought very well. There is no free lunch.

So measure twice & cut once or things can go wrong very fast and become even more expensive.

You might think this sounds a bit pessimistic. No this is an opportunity, especially for a Hyper-V MVP who happens to be a MCDBA Winking smile . The IT skills shortage is only growing bigger all over the planet, so not too much worries there, I won’t have to collect empty bottles for a living yet. The only so called “draw back” here could be that the environments I take care of have been virtualized and optimized to a high extend already. The reward for being good is sometimes not being able to improve things in orders of magnitude. Bad organizations living in a dream world, the ones without a solid grasp of the realities of functional IT in practice, might find that disappointing. Yes the “perception is reality” crowd. Fortunately the good ones will be happy to be in the best possible shape and they’ll invest money to keep it that way. Interesting times ahead.

Manually Merging Hyper-V Checkpoints

Posted on August 29, 2014 by workinghardinit

A Last-ditch Effort

First of all you need to realize this might not work. It’s a last-ditch effort. There is a reason why you have backups (with tested restores) and why you should monitor your environment for things that are not as they should be. Early intervention can pay off.

Also, see blog post on a couple of more preferred actions.

If you have lost checkpoints, you have basically lost data and corruption/data inconsistencies are very much a possibility and reality. If the files have been copied and information about what file is the parent the dates/timestamps are what you have to go by. You might not know for sure if you have them all.

Setting up the demo

For demo purposes, we take a test VM and ad files to indicate what checkpoint we’re at.

We start with ORGINAL.TXT on the desktop and we create a checkpoint, which we rename accordingly.

We add a file called CHECK01.TXT and we create a checkpoint, which we rename accordingly.

We add a file called CHECK02.TXT and we create a checkpoint, which we rename accordingly.

We add a file called NOW.TXT no more checkpoints are taken.

The file names represent the content you’d see disappear if you applied the checkpoint and we have reflected this in the name for the checkpoints.

As we want to merge all the snapshots and end up with a usable VHDX we’ll work back from the most recent differencing disk until all is merged. As you can see this is a straightforward situation and I hope you’ll never be running having to deal with a vast collection of subtrees.

Finding out what are the parents of avhdx files

In this demo, it’s pretty obvious what snapshots exist and what avhdx files they represent. We’ve even shown you the single tree visualized in Hyper-V Manager. In reality, bad things have happened and you don’t see this information anymore. So you might have to find out yourself. This is done via inspect disk in Hyper-V manager. If you’re confused about what the parent is of (a)vhdx files this tool will help you find out or show you what the most recent one was.

Sometimes the original files have been renamed or moved and that it will show you the last known valid parent.

Manually Merging the checkpoints

Remember to make a copy of all files as a backup! Also, make sure you have enough free disk space … you need working space! You might need another shot at this. As we want to merge all the snapshots and end up with a usable vhdx we’ll work back from the most recent differencing disk until all is merged in the oldest one which is the vhdx. You can look at the last modified timestamps to find out the correct order in which to work. The most recent avhdx is the one used in the virtual machine configuration file and locate the information for the virtual hard disk.

The configuration file’s avhdx is the one containing the “NOW” running state of the VM.

Note: You might find some information that you need to rename the extension avhdx to vhdx (or avhd to vhd). The reason for this was that in Windows 2008 Hyper-V Manager did not show avhd files in the Edit virtual disk wizard. You can still do this and it will still works, but you do not need to. Ever since Windows Server 2008 R2 avhd (and with since Windows Server 2012 avhdx) files do show up in Hyper-V Managers Disk edit.

For some insights as to why the order is important read this blog by Ben Armstrong What happens when a snapshot is being merged? [Hyper-V]

WARNING: If you did not start with the most recent one and work your way down, which is the easiest and least confusing way all is not lost. But you will have to reconnect the first more recent (a)vhdx to one to its new parent. This is needed as by merging a snapshot out of order more recent one will have lost it’s will have lost its original parent.

Here’s how to do this: Select reconnect. This is the page you’ll get if you’d start edit disk wizard as all other options are unavailable due to the missing parent.

The wizard will tell you what used to be the parent and allow you to select a new one. Make sure to tick the check box for Ignore ID mismatch or the reconnect will fail as you’re previous out of order merge has created a new a(vhdx). If your in this pickle by renaming (a)vhdx files or after a copy this isn’t needed by the way.

Follow the wizard after that and when your done you can launch the edit disk wizard again and perform a merge. It’s paramount that you do not mix up orders when doing so that you reconnect to the parent this or you’ll end up in a right mess. There are many permutations, keep it simple!. Do it in order. If you start having multiple checkpoint trees/subtrees things can get confusing very fast.

You might also have to reconnect if the checkpoints have lost their connection the what they know to be their last parent for other reasons. In that case, you do this and when that’s done, you merge. Rinse and repeat. The below walk-through assumes you have no reconnects to be done. If so it will tell you like in the example above.

Walk through:

Open the Edit Disk Wizard

Select the most recent avhdx & click “Next”

We choose to merge the avhdx

In our case into its parent disk

Verify the options are correct and click “Finish”

Let the wizard complete

That’s it. You’ve merged the most recent snapshot into it’s parent. That means that you have not lost the most recent state of the virtual machine as when it was running before you shut it down. This can be verified by mounting the now most recent avhdx and looking at the desktop for my user profile. You can see the NOW.txt text file is there!

OK, dismount the avhdx and now it’s rinse and repeat.

You do this over and over again until your merge the last avhdx into the vhdx.

Than you have the vhdx you will use to create a new virtual machine.

Make sure you get the generation right.

Assign memory

Connect to the appropriate virtual switch or not if you’re not ready to do this yet

Use your vhdx disk that’s the remaining result of your merging efforts

When you boot that virtual machine you’ll see that all the text files are there. It’s as if you’ve deleted the checkpoints in the GUI and retained “NOW” in the vhdx.

Last but not least, you can use PowerShell or even DiskPart for this but I found that most people in this pickle value a GUI. Use what you feel most comfortable with.

Thanks for reading and hope this helps someone. Do remember “big boy” rules apply. This is not safe, easy or obvious in each and every situation so you are responsible for everything you do in your environment. If your in to deep, way over your head, etc. call in some expert help.

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

Posted on August 25, 2014 by workinghardinit

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

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:

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.
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.
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.

Working Hard In IT

My view on IT from the trenches

Tag Archives: Hyper-V