SafeKit Quick Installation Guide with Hyper-V (hyperv.safe mirror module)

1. Prerequisites

The VM1 virtual machine files (VM1 configuration file, virtual hard disk...) must be put in a same folder: this folder will be replicated by SafeKit.

Make sure the virtual switch name(s) referenced by the virtual machine exist on both Hyper-V servers and corresponds to the same physical network.

It is important that all the files representing a VM (Virtual Machines/, Virtual Hard Disks/, .vmcx, .vmgs, .vmrs, .vhdx, ...) are in the same directory replicated by SafeKit. Else your VM will not reboot after replication. If you are not sure, take a snapshot or your VM before starting the procedure.

If all the files of VM1 are not in the same folder, use Hyper-V manager:

• Export VM1 in a folder, for example in D:Repli-Hyper-V
• This export will create a folder D:Repli-Hyper-VVM1 containing all VM1 files
• Remove VM1 from the inventory of Hyper-V manager
• Import VM1, previously exported, into Hyper-V manager

2. Launch the SafeKit console

• Launch the web console in a browser on one cluster node by connecting to http://localhost:9010.
• Enter admin as user name and the password defined during installation.

You can also run the console in a browser on a workstation external to the cluster.

3. Configure node addresses

• Enter the node IP addresses, press the Tab key to check connectivity and fill node names.
• Then, click on Save and apply to save the configuration.

4. Select a module

• In New module, click on the hyperv.safe module.

5. Configure the module

• Choose an Automatic start of the module at boot without delay.
• Normally, you have a single Heartbeat network on which the replication is made. But, you can define a private network if necessary (by adding a LAN at step 3).
• Put in VM_PATH, the root path of the replicated directory (D:Repli-Hyper-V).
• Enter in VM_NAME, the name of the virtual machine (VM1).

We assume that all VM1 files are in D:Repli-Hyper-VVM1 (see prerequisites). This directory will be replicated in real-time by SafeKit.

The NORMAL_STOP and FORCE_STOP values can be "stop", "save" or "off":

• "stop" shutdowns the VM when the module is stopped.
• "save" saves the current state of the VM (suspend) when the module is stopped.
• "off" turns off the VM (power off) when the module is stopped.

"stop" is recommended because it causes the shutdown then the reboot of the VM when the module is stopped and restarted. Thus, if the application inside the VM fails, it is restarted.

This will be the case, for example, when switching between primary and secondary roles.

6. Custom checker to detect VM malfunction

The custom checker sends heartbeat messages from the host to the VM at regular intervals. It is then the job of the Hyper-V Heartbeat Service installed in the VM to send a response to each of these heartbeat messages.

If the Hyper-V Heartbeat Service does not respond to the message (VM locked up, crashed or ceased to function), then the custom checker executes an action to restart the VM on the same Hyper-V node or on the other.

• Click on Checkers / Custom (see image).
• Just set a name of your choice in Resource name (example VM1). Resource name identifies the virtual machine with a resource name in SafeKit: custom.VM1.
• With restart in Action, the VM is restarted on the same Hyper-V node. After 3 unsuccessful restarts in 24 hours, the SafeKit hyperv module stops on the primary node and there is a failover of the VM on the secondary node.
• If you set stopstart in Action, there is a direct failover on the other Hyper-V node as soon as the VM does not respond to heartbeats.

8. Communication encryption (optional)

• Keep encryption of communication between nodes.

9. Save and apply

• Save and apply the configuration and scripts on both nodes.

10. Verify successful configuration

• Check the Success message (green) on both nodes and click on Monitor modules.

11. Start the node with up-to-date data

• If node 1 has the up-to-date replicated directory for VM1/, select it and start it As primary.

When node 2 will be started, all data will be copied from node 1 to node 2.

12. Wait for the transition to ALONE (green)

• Node 1 should reach the ALONE (green) state, which means that the start_prim script has been executed on node 1.

13. Start node 2

• Start node 2 with its contextual menu.
• Wait for the SECOND (green) state.

14. Verify that the cluster is operational

• Check that the cluster is green/green with VM1 running on the PRIM node and not running on the SECOND node.

Only changes inside files are replicated in real time in this state.

15. Testing

• Stop the PRIM node by scrolling down its contextual menu and clicking Stop.
• Verify that there is a failover on the SECOND node which should become ALONE (green).
• Check with Hyper-V manager that VM1 is running on node 2.

16. Automatic restart if a critical service fails inside the VM

If you want an automatic restart or failover when a critical service inside the VM fails, you can configure the Recovery properties of the service (see image).

First you must configure the custom checker previously described.

And then in Microsoft Service Manager inside the VM, select your critical service and in the recovery property of the service, you just have to configure shutdown of the VM when the critical service fails.

For that, in the Recovery options of your critical service, choose "Run a Program" on failures and in Run program options, set"C:WindowsSystem32shutdown.exe" and in "Command line parameters", set /s /c "service fails".

Of course, you can implement more subtle recovery with your own scripts. But just be aware that shutting down the VM will enable the custom checker in the host. The custom checker will detect that the Hyper-V heartbeat is no more responding and will restart the VM on the same Hyper-V server or will make a failover on the other Hyper-V server (depending on its configuration).

To test the feature, use Task Manager and kill the process (End task) associated to the critical service. A clean stop of the service through Service Manager or the "net stop" command does not trigger the recovery action inside Windows Service Manager.

17. Remove the start of VM1 in Hyper-V at boot

• In Hyper-V manager, configure VM1 with Automatic Start Action=nothing.

SafeKit controls the start and the stop of the VM on one node or the other.

18. Support

• For getting support, take 2 SafeKit Snapshots (2 .zip files), one for each node.
• If you have an account on https://support.evidian.com, upload them in the call desk tool.

19. If necessary, configure a splitbrain checker

• See below "What are the different scenarios in case of network isolation in a cluster?" to know if you need to configure a splitbrain checker.
• Go to the module configuration and click on Checkers / Splitbrain (see image) to edit the splitbrain parameters.
• Save and apply the new configuration to redeploy it on both nodes (module must be stopped on both nodes to save and apply).

Parameters:

• Resource name identifies the witness with a resource name: splitbrain.witness. You can change this value to identify the witness.
• Witness address is the argument for a ping when a node goes from PRIM to ALONE or from SECOND to ALONE. Change this value with the IP of the witness (a robust element, typically a router).
• Note: you can set several IPs separated by white spaces. Pay attention that the IP addresses must be accessible from one node but not from the other in the event of network isolation.