For some storage arrays, the vendor will provide its own multipathing software to manage multipathing for the array’s physical and logical devices. In this case, you should follow the vendor’s instructions for configuring multipathing for those devices.

Perform the following disk management tasks before you attempt to configure multipathing for a physical or logical device that has multiple paths:

The Linux software RAID management software runs on top of multipathing. For each device that has multiple I/O paths and that you plan to use in a software RAID, you must configure the device for multipathing before you attempt to create the software RAID device. Automatic discovery of multipathed devices is not available. The software RAID is not aware of the multipathing management running underneath.

High-availability solutions for clustering typically run on top of the multipathing server. For example, the Distributed Replicated Block Device (DRBD) high-availability solution for mirroring devices across a LAN runs on top of multipathing. For each device that has multiple I/O paths and that you plan to use in a DRDB solution, you must configure the device for multipathing before you configure DRBD.

Volume managers such as LVM2 and EVMS run on top of multipathing. You must configure multipathing for a device before you use LVM2 or EVMS to create segment managers and file systems on it.

When using multipathing in a virtualization environment, the multipathing is controlled in the host server environment. Configure multipathing for the device before you assign it to a virtual guest machine.

The multipath-tools package automatically detects the following storage arrays:

In general, most other storage arrays should work. When storage arrays are automatically detected, the default settings for multipathing apply. If you want non-default settings, you must manually create and configure the /etc/multipath.conf file. For information, see Section 5.4.5, “Creating and Configuring the /etc/multipath.conf File”.

Hardware that is not automatically detected requires an appropriate entry for configuration in the DEVICES section of the /etc/multipath.conf file. In this case, you must manually create and configure the configuration file. For information, see Section 5.4.5, “Creating and Configuring the /etc/multipath.conf File”.

Consider the following caveats:

The following storage arrays have been tested with SUSE Linux Enterprise Server:

Most other vendors’ storage arrays should also work. Consult your vendor’s documentation for guidance. For a list of the default storage arrays recognized by the multipath-tools package, see Section 5.2.3.1, “Storage ArraysThat Are Automatically Detected for Multipathing”.

Storage arrays that require special commands on failover from one path to the other or that require special nonstandard error handling might require more extensive support. Therefore, the Device Mapper Multipath service has hooks for hardware handlers. For example, one such handler for the EMC CLARiiON CX family of arrays is already provided.

	Important
Consult the hardware vendor’s documentation to determine if its hardware handler must be installed for Device Mapper Multipath.

The multipath -t command shows an internal table of storage arrays that require special handling with specific hardware handlers. The displayed list is not an exhaustive list of supported storage arrays. It lists only those arrays that require special handling and that the multipath-tools developers had access to during the tool development.

	Important
Arrays with true active/active multipath support do not require special handling, so they are not listed for the multipath -t command.

A listing in the multipath -t table does not necessarily mean that SUSE Linux Enterprise Server was tested on that specific hardware. For a list of tested storage arrays, see Section 5.2.3.2, “Tested Storage Arrays for Multipathing Support”.