Posts Tagged ‘Failover Cluster’

Just recently I was running into some very strange issues with my Hyper-V Cluster. we have numerous NICs to allow for redundancy and better throughput for our clustered environment. We have a total of 11 NICs on our server to cater for Guest LAN, iSCSI, guest iSCSI (as we present SAN storage directly to the Guests), HeartBeat and Live Migration. So, I was getting a little concerned when I was performing maintenance and/or “Live Migrations” and my VMs were losing network connectivity both on LAN connections and iSCSI connections which was causing major issues with my VMs needing external storage as this was mostly SQL or file shares. So time to start troubleshooting.

First stop would obviously be the NICs on the hosts and I spent some time checking all the NICs and ensuring they are cabled correctly. Not the world’s easiest job considering the amount of network cables we have in our cabinets. We have numerous Hyper-V nodes, all with 11 NICs excluding Management and iDRAC. So we are talking hundreds of cables. However, I trudged through it and put a check mark next to it – no issues there.

So, several hours and days later and cursing and swearing all the network cables, velcro and cable ties in my cabinets, it was time to move on. So, it was NOT a physical network issue. Time to give a little further. My next stop was the Hypervisor layer.

I start diving through the Hypervisor and I found “gold” here, (I actually mean the cause of my issue). Enter Hyper-V Networking. Please allow me to clarify this. The networking was not the issue but what someone/something had done, the truth here will never be known. I found that I had duplicate Virtual Network created.

So, for each physical NIC i had in the server and was using for the Virtualization, I had 2 networks. 1 connected to the “External Network” and here is the kicker, 1 connected to the “PRIVATE” network. So with a little troubleshooting and deal of understanding Virtual Switches, I was able to return my cluster to it’s former 100% redundant glory. After removing ALL the private networks and there were many on all my Nodes, I was able to Live Migrate and patch/maintain to my heart’s content.

Gotta love Virtualization.

Hopefully this will help someone else as well.

The lesson here is to keep a good eye on your Virtual Environment and always check the basics.

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So, now you are at the point where you need to present a CSV Volume to your cluster.

I have created this guide to make your life a little easier. Doing this is actually quite simple, but there are a few gotchas.

Gotcha 1 : If you create / carve the LUN and forget to allow multiple access, only the first IQN / WWN will be able to access it.

Gotcha 2 : If you present the disk to the “Storage” (highlighted below) portion of your cluster and do NOT create a simple volume, you will not be able to do this from Disk Management as the Cluster will have a lock on it. Simply delete the volume from the “Storage” and then create the simple volume.

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Okay, so getting past that.

Step 1: Create / Carve the LUN from your Storage.

Step 2: Remember to allow multiple access to the volume.

Step 3: Present the Storage to all the Nodes in the Cluster.

Step 4: Bring the disk online

Step 5: Initialize the disk

Step 6: Create a simple volume, there is NO need to assign a drive letter.

Step 7: Open Failover Cluster Manager and Select “Storage” and Click “Add a disk”

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Step 8: Add the Disk, you should see the newly presented disk, select the disk and click OK. The disk will show up as online under “Available Storage”. You can rename the disk according by double clicking the disk and changing the name in “Resource Name”

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Step 9: Now it is time to make it a “CSV”, Click “Cluster Shared Volumes” and click “Add Storage”

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Step 10: Select the Disk you want to add and click “OK”

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Disk is now online and a CSV.

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