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Monday, September 5, 2011

2008 R2 Failover Cluster - HA Senario

Having the system with no single point of failure has been my dream since I started working at the current office over three years ago.
I've been insisting the company's management how important to have redundant system since then. Finally I got approval to purchase two brand new servers with multiple NICs, SAN and 2 Catalyst switches for the cluster system. All VMs are running on the cluster. My fear has gone!

HP ProLiant DL380 G7 (2 x Xeon 5650, 24GB, 8 x Gigabit NIC)
2 x Cisco Catalyst 2960
HP MSA2324i G2

Network Setting:
2 x Cluster ( -- >  NIC Teaming
3 x SAN (
3 x LAN (  -- >  NIC Teaming

2 x Microsoft Windows 2008 R2 Datacenter
(Failover Cluster is not available for Standard Edition. You need Enterprise or Datacenter. )

1. Install 2008 R2 OS and install the latest NIC driver, all patches and updates .
Don’t forget to update drivers also. All nodes in the cluster must have the same drivers, updates and patches.

2. Configure Networks
You should have multiple networks separated from each other depending on their functions. 5 dedicated networks shown below is ideal if you can afford. In my  case, I have dedicated netowrks for 1 and 5 the rest, 2, 3 and 4 share one network.
  1. Cluster communication
  2. Live Migration
  3. Client communication
  4. Management
  5. Storage
The below table shows required protocols for each network. The cluter network uses SMB and IPv6. Make sure those protocols are enabled in the cluster network properties.

Client for Microsoft Netowrks
File & Printer sharing
Cluster Network

Also NetBIOS should be disabled for cluster and SAN.

Previously I often heard that NIC teaming didn't work with Hyper-V well. Many NIC vendors supports teaming on Hyper-V now. If you are looking to NIC teaming, check your hardware vender’s website and use the driver supports teaming and Hyper-V. 

When HP NIC Teaming is used in conjunction with Hyper-V, the order of installation becomes crucial. Each component has to be installed in the certain order.
Add Hyper-V roll -- > HP NIC Teaming Utility -- > Configure Teaming -- > Create Hyper-V

3. Install the Failover Cluster feature
Cluster installation is straight forward and many documentations are available, so I will skip this part.

4. Optimizing networks
Once the Failover Cluster wizard complete, you will see the Networks section in the left pane in the Failover Cluster Manager. 
Configure which network the clustered shared volume uses by setting properties of each netowrk.

Check "Allow cluster network communication on this netowrk" for the cluster communication. If you want clients to use the netowrk, check "Allow clients to connect through this network" For SAN, check "Do not allow cluster netowrk communication on this network".
You can view the configuration by running Powershell commandlets.

Imort-Module FailoverClusters

Get-ClusterNetowrk | ft name, role, autometric, metric

Role=1: Use this network for CSV communication.
Role=3: Use this network for CSV communication and clients.
Role=0: CSV doesn't use this netowork
The network with the smalles metric value is used for the cluster communication. The network with the second smallest metric is used for Live Migration.

I explained the details focusing on the netowrk configuration and tuning up because not so may articles and documentations cover the network in detail.

I just found and read a good article today by John Savill, "Introduction to Cluster Shared Volumes" in Windows ITPro September issue. If you want to know more about the cluster, you should check it out.