SafeKit Quick Installation Guide with KVM (kvm.safe Mirror Module)

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 kvm.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 (/var/lib/libvirt/images).
• Enter in VM_NAME, the name of the virtual machine (vm1).

We assume that the VM1 files are in /var/lib/libvirt/image/vm1/ (see prerequisites). This directory will be replicated in real-time by SafeKit.

6. Custom checker to detect VM malfunction

The custom checker checks if the VM is running (with the 'virsh domstate' command). If the VM is not running, the custom checker automatically restarts the VM on the same KVM node or on the other.

• Click on Checkers / Custom (see image).
• Resource name identifies the virtual machine with a resource name in SafeKit: custom.VM_NAME_check.
• With restart in Action, the VM is restarted on the same KVM node. After 3 unsuccessful restarts in 24 hours, the SafeKit kvm 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 KVM node as soon as the VM is not running.

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 KVM tools that VM1 is running on node 2.

16. Replicating snapshots

The directory that contains the snapshot xml files is:

/var/lib/libvirt/qemu/snapshot/%VM_NAME%

where VM_NAME is the name of the virtual machine (vm1).

Note: If no snapshot has been created, create one to generate the directory (else the SafeKit configuration will fail).

To replicate it:

• In the module configuration, click on Advanced Configuration (see image) to edit userconfig.xml.
• Insert the lines below into the <rfs> section of userconfig.xml:

  <replicated dir="/var/lib/libvirt/qemu/snapshot/%VM_NAME%" mode="read_only"> </replicated>

• Save and apply the new configuration to redeploy the modified userconfig.xml file on both nodes (module must be stopped on both nodes to save and apply).
• Create snapshots on the PRIM node either through virt-manager or a command line:

  virsh snapshot-create-as vm1 snapshot-name

  Note: when creating a snapshot with a command line, you have to refresh the snapshot view into virt-manager.

Snapshots created on the PRIM node are operationnal on node 2 after failover, but not listed on node 2.

• For importing a snapshot on node 2, you have to run the command:

  virsh snapshot-create --redefine vm1 /var/lib/libvirt/qemu/snapshot/vm1/snapshot-name

• The command line for listing all snapshots of vm1 is:

  virsh snapshot-list vm1

17. 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.

18. 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.