Configuring Multipathing I/O Features

You can configure the multipathing features for FC devices to control all supported FC HBAs. Multipathing is disabled by default for FC devices on SPARC based systems, but is enabled by default on x86 based systems. Configuration of the multipathing features depends on how you intend to use your system.

Note - The multipathing feature is not available for parallel SCSI devices, but is available for FC, SAS, and iSCSI devices.

Multipathing Considerations

Before you change multipathing configuration, note the following considerations. Then follow the instructions for your machine architecture (SPARC or x86) described in the subsequent sections. Some devices need to be properly configured to work with the multipathing software. Refer to your storage array documentation for details on the device-specific configuration for your device.

Device-specific and device name change considerations

In the /dev and /devices trees, multipathed devices receive new names that indicate that they are under multipath control. A device therefore will have a different name from its original name when it is under multipath control.

Device name with multipath disabled:
```
/dev/dsk/c1t1d0s0
```
Device name with multipath enabled:
```
/dev/dsk/c0t60003BA27D5170003E5D2A7A0007F3D2d0s0
```
Therefore, applications that use device names directly must be configured to use the new names whenever you change a multipath configuration from disabled to enabled or vice versa.
Updates to /etc/vfstab entries and dump configuration

The system’s /etc/vfstab file and the dump configuration also contain references to device names. On both SPARC based and x86 based systems, the stmsboot command automatically updates the /etc/vfstab file dump configuration with the new device names. If you have application-dependent file systems which are not listed in the file /etc/vfstab, you can use the stmsboot command to determine the mapping between the old and new device paths.

Caution - If you have run the devfsadm -C or performed a reconfiguration boot, the old device paths will not exist and the stmsboot -L command will fail to provide this information.

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	Oracle Solaris SAN Configuration and Multipathing Guide Oracle Solaris 10 1/13 Information Library