1.1 Sun Cluster Overview

The Sun Cluster system is a software environment that provides high availability (HA) support for data services and parallel database access on a cluster of servers (Sun Cluster servers). The Sun Cluster servers run the Solaris 2.6 or Solaris 7 operating environment, Sun Cluster framework software, disk volume management software, and HA data services or parallel database applications (OPS or XPS).

Sun Cluster framework software provides hardware and software failure detection, Sun Cluster system administration, system failover and automatic restart of data services in the event of a failure. Sun Cluster software includes a set of HA data services and an Application Programming Interface (API) that can be used to create other HA data services by integrating them with the Sun Cluster framework.

Shared disk architecture used with Sun Cluster parallel databases provide increased availability by allowing users to simultaneously access a single database through several cluster nodes. If a node fails, users can continue to access the data through another node without any significant delay.

The Sun Cluster system uses Solstice DiskSuite, Sun StorEdge Volume Manager (SSVM), or Cluster Volume Manager (CVM) software to administer multihost disks--disks that are accessible from multiple Sun Cluster servers. The volume management software provides disk mirroring, concatenation, striping, and hot sparing. SSVM and CVM also provide RAID5 capability.

The purpose of the Sun Cluster system is to avoid the loss of service by managing failures. This is accomplished by adding hardware redundancy and software monitoring and restart capabilities; these measures reduce single points of failure in the system. A single-point failure is the failure of a hardware or software component that causes the entire system to be inaccessible to client applications.

With redundant hardware, every hardware component has a backup that can take over for a failed component. The fault monitors regularly probe the Sun Cluster framework and the highly available data services, and quickly detect failures. In the case of HA data services, HA fault monitors respond to failures either by moving data services running on a failed node to another node, or, if the node has not failed, by attempting to restart the data services on the same node.

Sun Cluster configurations tolerate the following types of single-point failures:

• Server operating environment failure because of a crash or a panic

• Data service failure

• Server hardware failure

• Network interface failure

• Disk media failure