Axcient Replibit has the ability to combine multiple Appliances or Vaults at a location into a cluster for management purposes. This means that the management database on the devices is merged and shared, and the Web Interface presents a consolidated view of all Protected Systems residing on any device within the cluster. This process does not perform any data storage consolidation or filesystem clustering services; it is strictly a merging of the database information.
Important: Due to the complexity induced by the necessity of maintaining a quorum of active nodes, and possible user confusion over which device a particular Protected System resides on, Axcient Replibit does not recommend enabling clustering unless there is a compelling need to do so. Please perform at your own risk.
Notes on Clustering
The database engine on all devices in a cluster is reconfigured as a true network clustered service as soon as any additional nodes are added to a stand-alone deployment. Changes are replicated synchronously to all members, and a quorum must be established to identify the primary node before any write operations are allowed in the database.
- To form a quorum, a majority of member nodes must be online and in communication with one another. If no majority exists, no node will be promoted to Primary and the database will remain in read-only mode.
- In order for a quorum to exist, there must be an odd number of nodes in the cluster. It is impossible to establish a majority with an even number of nodes.
- In order to facilitate maintaining an odd number of nodes, Axcient Replibit utilizes the Arbiter service that can be deployed onto a Windows system when there are an even number of Replibit devices in the cluster.
- The Arbiter node installer can be downloaded from the Downloads page on any device. Install the Arbiter on any Windows system to deploy a passive database replica, which facilitates the quorum.
- The Arbiter is not resource intensive, and should be deployed in the same site and subnet as the Axcient Replibit devices in the cluster.
To set up a cluster:
- Deploy a node in stand-alone mode as usual. When you have deployed and configured the first node, you must enable it for clustering.
- Log in to the Web Interface and select the Cluster Management menu pane.
- Select the Enable Clustering checkbox.
Once enabled, the cluster will consist of this single device as the Primary node with no Arbiter mode.
Note: A cluster must consist of an odd number of nodes. In order to facilitate this, Replibit provides a virtual node called the Arbiter. If you intend to deploy an even number of actual Appliance or Vault devices, you will also need to deploy the Arbiter in order to make the total node count odd.
- If necessary, download the Arbiter software onto a Windows machine from the Downloads menu of any Appliance. The Arbiter should be installed on a Windows system located on the same LAN as the other members of the cluster.
- When the Arbiter has been installed, navigate to the Cluster Management menu on the Replibit device.
- In the Arbiter Node field, enter the IP address of the Windows Server and click Save.
- Now you can deploy a second clustered device at the same location. When performing the initial configuration of the device from the Web Interface, select the Add machine to existing Cluster radio button instead of the First machine in Cluster radio button.
- You will be prompted for the IP address of an existing member of the cluster. Enter the IP address of an already configured Replibit device, not the Arbiter node.
- Complete the setup of the device, and configure the Storage Pool as normal.
When you have completed configuration of the Storage Pool, you will be able to access the Settings menu pane. You will notice that most of the available options and settings are globally shared with all members of the cluster. Only machine specific settings, like Machine Name and Network Settings, are independently configurable. Changing any of the shared settings parameters (for example, Password) affects all members of the cluster. The Protected Systems page will list all Protected Systems residing in the cluster on any node.