Multihosted Data

The highly available global file systems' disksets are multihosted so that when a physical host crashes, one of the surviving hosts can access the disk. For a data service to be highly available, its data must be highly available, and thus its data must reside in the global HA file systems.

The global file system is mounted on disk groups, which are created as independent entities. The user can choose to use some disk groups as mounted global file systems and others as raw devices for use with a data service, such as HA Oracle.

A data service might have command-line switches or configuration files pointing to the location of the data files. If the data service uses hard-wired path names, you might change the path name to a symbolic link that points to a file in a global file system, without changing the data service code. See "Using Symbolic Links for Multihosted Data Placement" for a more detailed discussion about using symbolic links.

In the worst case, the data service's source code must be modified to provide some mechanism for pointing to the actual data location. You might do this by implementing additional command-line switches.

Sun Cluster supports the use of UNIX UFS file systems and HA raw devices configured in a volume manager. When the system administrator installs and configures Sun Cluster, he or she must specify which disk resources to use for UFS file systems and which for raw devices. Typically, raw devices are used only by database servers and multimedia servers.