Multipathing and FSPM Plug-In Libraries Descriptions

The Oracle FS Path Manager (FSPM) provides plug-in libraries for the Multipath Daemon that automatically adjust to differences between different versions of Multipath Tools to ensure that FSPM works with the version of the Multipath Daemon provided by the operating system.

As the FSPM plug-in is loaded, information from the Multipath Tools is compared with information in a FSPM parameter file and if the information matches, then all functions provided by FSPM are used.

If the information does not match, LUN management is passed through to the most suitable libraries provided by the operating system. This means that the FSPM functions of static load balancing support and path preference by protocol are not available. The operating system Multipath Tools continue to report that the Multipath Tools are using the FSPM plug-in as the LUN management pass-through is not visible to Multipath Tools.

When FSPM is using the native operating system plugins in this way, it appends the word native to the FSPM version string displayed in the Oracle FS System Manager (GUI). For example, the FSPM version might be displayed under SAN Hosts Oracle FS Path Manager Version as 4.0.x native (where x is the release number such as 4.0.2). If you see FSPM version listed as native, contact Oracle Customer Support for a FSPM update to provide full support for your version of Multipath Tools.

As FSPM is installed, FSPM integrates into the Multipath Tools configuration on the system. FSPM copies libraries and programs into the appropriate directories and creates or modifies the Multipath Tools configuration file which is named as /etc/multipath.conf. If a different version of Multipath Tools is subsequently installed, these integrations could be overridden. FSPM uses the RPM ‘trigger’ mechanism to automatically set up or refresh the FSPM integration into Multipath Tools whenever any of the following events happen:

FSPM is installed or upgraded
The OS Multipath Tools package is upgraded
The FSPM parameter file is upgraded
The OS Multipath Tools Libraries are upgraded

An example of this process is where an administrator uses the yum update tool to apply operating system patches that install a different version of Multipath Tools which does not match the information in the FSPM parameter file, the FSPM installation immediately and automatically reintegrates into the new Multipath Tools, and starts using the native ALUA prioritizer instead of the FSPM prioritzer.

When a new version of the FSPM parameter file is installed that supports the version of the Mulitpath Tools, installing the FSPM parameter file causes a reintegration of FSPM. The reintegration enables full FSPM support and static load balancing and path preference is restored.

An advantage of using the parameter file is that as Multipath tools are updated and released, the FSPM parameter file is updated and can be installed into the existing FSPM installation. When you install the parameter file, FSPM is reconfigured to match the Multipath tools and all functions are restored as described earlier. This avoids installing a new version of FSPM.

Note: The FSPM parameter file is included in the FSPM software package and can be installed separately. The process is described in this document.

Whenever FSPM modifies /etc/multipath.conf, FSPM saves a copy first. If FSPM is integrating itself into the Multipath Tools, the saved file is named as follows: /etc/multipath.conf.fspm.in.YYYY-MM-DDThh:mm:ss . In this example, YYYY-MM-DDThh:mm:ss represents the date and time as shown here as: /etc/multipath.conf.fspm.in.2014-03-27T16:57:37. If FSPM is being installed, the saved file is named as follows: /etc/multipath.conf.fspm.out.YYYY-MM-DDThh:mm:ss. You can use these saved files to check any changes which FSPM has made if necessary.