PowerShell: Monitoring DrainStatus of a Hyper-V Host & The Time Limited Value of Information In Beta & RC Era Blogs

Posted on March 1, 2013 by workinghardinit

I was writing some small PowerShell scripts to kick pause and resume Hyper-V cluster hosts and I wanted to monitor the progress of draining the virtual machines of the node when pausing it. I found this nice blog about Draining Nodes for Planned Maintenance with Windows Server 2012 discussing this subject and providing us with the properties to do just that.

It seems we have two common properties at our disposal: NodeDrainStatus and NodeDrainTarget.

So I set to work but I just didn’t manage to get those properties to be read. It was like they didn’t exist. So I pinged Jeff Wouters who happens to use PowerShell for just about anything and asked him if it was me being stupid and missing the obvious. Well it turned out to be missing the obvious for sure as those properties do no exist. Jeff told me to double check using:

Get-ClusterNode MyNode -cluster MyCluster | Select-Object -Property *

Guess what, it’s not NodeDrainStatus and NodeDrainTarget but DrainStatus and DrainTarget.

What put me off here was the following example in the same blog post:

Get-ClusterResourceType "Virtual Machine" | Get-ClusterParameter NodeDrainMoveTypeThreshold

That should have been a dead give away. As we’ve been using MoveTypeTresHold a lot the recent months and there is no NodeDrain in that value either. But it just didn’t register. By the way you don’t need to create the property either is exists. I guess this code was valid with some version (Beta?) but not anymore. You can just get en set the property like this

Get-ClusterResourceType “Virtual Machine” -Cluster MyCluster | Get-ClusterParameter MoveTypeThreshold

Get-ClusterResourceType “Virtual Machine” -Cluster MyCluster | Set-ClusterParameter MoveTypeThreshold 2000

So lessons learned. Trust but verify Smile . Don’t forget that a lot of things in IT have a time limited value. Make sure that to look at the date of what you’re reading and about what pre RTM version of the product the information is relevant to.

To conclude here’s the PowerShell snippet I used to monitor the draining process.


Suspend-clusternode –Name crusader -Cluster warrior -Drain

Do
{
    Write-Host (get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -ForegroundColor Magenta    
    Sleep 1
}
until ((get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -ne "InProgress")

If ((get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -eq "Completed")
{
    Write-Host (get-clusternode –Name “crusader” -Cluster warrior).DrainStatus -ForegroundColor Green
}

Which outputs

Ben Armstrong Interviewed by Carsten Rachfahl on Windows Server 2012 Hyper-V

Posted on February 26, 2013 by workinghardinit

During the 2013 Global MVP Summit Carsten Rachfahl (@hypervserver) interviewed Ben Armstrong (@VirtualPCGuy.) who is the senior program manager for Hyper-V and as such the guy who has the honorable job of herding us cats Smile during the MVP Summit (he does an excellent job). Click the picture below to view the interview or visit Videointerview mit Ben Armstrong über Hyper-V

This interview took place at the CenturyLink Field stadium in Seattle (home of the Seahawks) where we had our little summit party and turned out to be a real gem and we have to thank Carsten for his efforts and Ben for giving the interview. Watch it all to the end to see that we’re all pretty convinced about the qualities of Windows Server 2012 Hyper-V!

My Impressions on Windows Server 2012 Hyper-V Cookbook

Posted on February 18, 2013 by workinghardinit

Having read Windows Server 2012 Hyper-V Cookbook I can safely say that if you need get up to speed with Hyper-V in Windows Server 2012 this is a great book for this purpose.

Having met Leandro Carvalho that’s not a surprise. What is pretty impressive is how he managed to get all you need to know to get going inside of one book that you can still lift with one hand. Now this is not going to make you a veteran Hyper-V enterprise architect over the weekend but it will help you get a well set up and functional Hyper-V environment running, monitored and protected. If you are already familiar with Hyper-V form previous Windows versions this book will also get you up to speed on a lot of the most important new features and improvements.

Now a mere 305 pages are not enough to go into depth on every subject but this book will make a fine learning tool to set up a lab and take your first Windows Server 2012 Hyper-V servers / clusters into production. It also tackles some of the more intimidating stuff to some people like in place upgrades of Hyper-V clusters and disaster recovery. Details like CSV cache, Port ACL and their significance in the new Hyper-V version are not forgotten. I like that attention to detail. Knowing the vastness of what’s new in Windows Server 2012 Hyper-V I’m impressed at how well organized and effective the information is presented. So if you need to get started with Hyper-V, do it here with this book. It will make for a fine foundation to build on and move on to investigate the numerous network configurations, the VHDX format, SMB 3.0 goodness etc.

Exploring Hyper-V Virtual Switch Port Mirroring

Posted on February 1, 2013 by workinghardinit

Windows Server 2012 brings us many new capabilities and one of those is port mirroring. You can now configure a virtual machine NIC (vNIC) who’s traffic you want to monitor as the source in the Advanced Features of the Network Adapter settings. The vNIC of the virtual machine where you’ll run a network sniffer, like Network Monitor or WireShark, against is set to “Destination”. It’s pretty much that simple to set up. Easy enough.

On the vNIC you want to monitor the traffic to and from the VM, under Settings, Network Adapter (choose the correct one), under Advanced Features you select “Source” as Mirroring mode. In this example we’re going to monitor data traffic to and from the guest Columbia.

On the destination VM we have a dedicated vNIC set up called “Sniffie”

On the guest VM Pegasus, where we’ll capture the network traffic via a dedicated vNIC (“Sniffie”), we set that vNIC (virtual port) to “Destination” as Mirroring node:

So now let’s start pinging a host (ping –t crusader) on our Source VM Columbia

And take a look on the Destination vNIC on virtual machine Pegasus where we’re capturing the traffic. The “Sniffie” NIC there is set to destination as Mirror Mode. Look at the ICMP echo reply from form 192.168.2.32 (Crusader host). Columbia is at 192.168.2.122 sending out the ICMP echo request.

Pretty cool!

Some Technicalities

So deep down under the hood, it’s the switch extension capabilities of the Hyper-V virtual switch that are being leveraged to achieve port sniffing. This is just one of the many functionalities that the Hyper-V extensible switch enables. The Hyper-V extensible switch itself uses port ACLs to set a rule that forwards traffic from one virtual port to another virtual port. For practical reasons translate virtual port to vNIC in a VM and this translates into what we shown above. While it’s good to know that port ACLs are what is used by the extensible switch to do enable all kinds of advances features like port mirroring but you don’t need to worry about the details to use it.

Things to note

Initially many of us made the assumption that we’d be able to sniff the traffic form a virtual port to a port on their physical switch. This is not the case. Basically, in box, it’s a source VM that mirrors it’s network traffic form one or more virtual ports (vNICs) to a destination VM’s one or more virtual ports (vNIC).

You can send many sources to one destination. That’s fine. You could also define more destinations on the same host but that’s not really wise and practical as far as I can see. All in all, you set it up on when needed on the source VM and you keep a destination VM with a sniffer around for the sniffing.

Also keep in mind that all this works within the boundaries of the same host. Which means that if you want to monitor a VMs network traffic when it moves across nodes in a cluster you’ll have to have "destination” virtual machine on each host. This means that when a source VM is live migrated it will mirror the traffic to that local destination VM. That works.

You could try and live migrate source & destination VMs to the same host but this is not feasible in real life. For one the capture doesn’t survive after a life migration as your sniffer loses connectivity to virtual Port / vNIC.

Don’t be too disappointed about this. Port mirroring is not meant to be a permanent situation that you need to keep highly available anyway, bar some special environments/needs.

Whilst is it true that out of the box you can’t do stuff like sending the mirrored traffic form a guests vNIC/virtual port to a physical switch port where you attach your network sniffer laptop or so. If you throw on the CISCO Nexus 1000V it replaces the Microsoft in box “Forwarding Extensions” and than it’s up to CISCO’s implementation to determine what you can or can’t do. As this stuff is right up their sleeve they allow the Cisco Nexus 1000V mirrors traffic sent between virtual machines by sending ERSPAN to an external Cisco Catalyst switch. I have not had the pleasure of ~~playing~~ working with this.

Anyway, I hope this help to explain things a little. Happy sniffing and don’t get yourself into trouble, follow the rules.

Working Hard In IT

My view on IT from the trenches

Tag Archives: Hyper-V