Note: Clustering is a large and complex topic. This chapter covers clustering as it applies to maximizing the availability of the Loftware Print Server (LPS) in your enterprise. Some of the points made here do not necessarily apply to other “cluster aware” applications. If you have not set up cluster aware applications in the past, find someone who can assist you.
Clustering is a feature of the Loftware Print Server Edition. In its most basic form, two servers are connected together with a central storage device between them as shown in the following figure. The cluster service makes the two machines appear as a single virtual server on the network. Client applications make their connections to this virtual server. If an application “goes down” due to a hardware or software failure, it is automatically restarted on the secondary server. This is referred to as a “failover.”
Figure 4-A: Basic Cluster Architecture (Active/Active)
At this time, Loftware is using the Microsoft Cluster Service (MSCS) exclusively. The Microsoft Cluster Service architecture is designed to work with standard Windows Server storage drivers interfacing with SCSI devices. The storage device, typically a RAID system, must be connected to both nodes in the cluster for failover to work properly. Shared storage devices must be formatted using NTFS.
Clustering requires special hardware, software, and expertise. You cannot simply “network” two computers together. The extra expense of hiring a knowledgeable person who is intimately familiar with clustering computers together is well worth it. Loftware cannot help you with the setup or support of your hardware.
