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High Availability Cluster

Highly reliable, highly expandable cluster solutions

InterWorx

Clustering is a rather generic term when it comes to computers and there are a variety of clustering mechanisms and uses. The term clustering usually denotes a group of computers (2 or more, dubbed nodes) working together as a unit on a task. For our clustered configurations we prefer to use InterWorx, a fully cluster aware control panel for ease of administration, which also employs a load balancer that distributes incoming traffic to one of the nodes in the cluster. As traffic flow to the cluster increases, more nodes can be added at any time to distribute the load over a broader range of servers. To learn more about the Interworx product you can visit their web site at http://www.interworx.com.

These are sample Interworx based cluster setups. As the possibilities are basically endless as to what type of configuration you may require, please request a quote or call sales at 312-602-2689 (Option 2). We will be more than happy to assist you in selecting a cluster setup that can meet your needs. For optimum reliability, we recommend you purchase a cluster with at least three servers, one acting as the storage manager and cluster manager and two as a load balanced/redundant pair of web servers, and that the cluster/storage managing system have a RAID array. While it is not optimal for utmost reliability, you can have a cluster of two servers, which would be perfect for sites that have outgrown the resources of a single system. Servers can be added or removed from the cluster at any time and there is no limit to the number of systems that can be in a cluster.

Example Configurations

Why an InterWorx Cluster?

Clustering allows you to harness the power of multiple servers acting as a single unit. The historical problem with clustering configurations for most users is the maintenance processes. Maintaining a cluster traditionally requires a system administrator to architect, install and monitor the cluster. There are key decisions to be made regarding how the cluster is architected.

Some of these questions can be answered by simply purchasing a hardware solution that serves the purpose. These solutions work well, but at exorbitant cost for the average user. While purchasing a hardware solution may solve the technical problems, the management problems will remain. Interworx along with the managed services of Steadfast Networks solve all of these problems as Interworx gives you the easy to use management interface and load balancer, while Steadfast Networks can manage your storage infrastructure and architecture/engineering.

The InterWorx Solution

InterWorx uses a collection of open source components and combines them with the InterWorx API system allowing a single InterWorx box, the Cluster Manager, to control and manage an entire cluster. From the Cluster Manager node you can add and delete nodes from the cluster graphically without ever having to use a shell utility. The Cluster Manager also acts as the main console for account management. Any accounts added on the Manager will instantly be propagated to all InterWorx nodes in the cluster via the InterWorx API subsystem. Adding and deleting nodes and accounts is made simple by use of the InterWorx interface.

Load Balancing

The load balancer, provided by the Linux Virtual Server Project (LVS) is a robust software load balancing solution. LVS has many large installations and is a proven technology. If you're already familiar with LVS you'll be happy to know that you can do any and all configuration for LVS from the command line as you can with most Interworx services. We also provide a clean graphical interface on the Cluster Manager to configure all aspects of the load balancing setup, including RRD graphs so you can track the load balancer as it operates.

Cluster Storage

Interworx clusters use a shared NFS storage mechanism to mitigate any overt data synchronization of data. Asynchronous data synchronization (usually done via rsync) can confuse end-users when using a cluster as data uploaded to one node may not be immediately available on all nodes. The NFS solution provides a synchronous data source where all nodes see exactly the same data at the same time. The shared storage device can be as simple as a single drive on your cluster manager, but we highly recommend you use a RAID array or our Enterprise SAN/NAS for your data storage needs.

Using Cluster Services

The InterWorx clustering solution makes a cluster of servers act as a single, virtual server. This is best conveyed by using basic services such as IMAP, POP3, SSH, etc. You can SSH to any of the clustered nodes, edit files and the entire cluster instantly sees the change. If you need to hand edit a PHP script via SSH every apache instance on every node will process the change as soon as you save the file. This is also true for POP3 and IMAP. You can check POP3 e-mail from any node and you will get the same result. This allows for easy load balancing of services beyond HTTP and HTTPS.