Solaris Fibre Channel and Storage Multipathing Administration Guide

Solaris Fibre Channel and Storage Multipathing Administration Guide

C H A P T E R 4

Configuring Multipathing Software

This chapter explains how to configure multipathing feature for FC devices provided in the Solaris 10 OS. It also provides the considerations while enabling or disabling multipathing feature on SPARC based systems, x86 based systems, per-port basis and third-party storage devices.

This chapter contains the following sections:

Configuring Multipathing

Enabling or Disabling Multipathing

Enabling or Disabling Multipathing on SPARC Based Systems

Enabling or Disabling Multipathing on x86 Based Systems

Enabling or Disabling Multipathing on a Per-Port Basis

Disabling Multipathing on Third-Party Devices

Configuring Automatic Failback

Configuring Third-Party Storage Devices

Displaying Device Name Changes

Configuring Multipathing

The multipathing feature for FC devices can be configured to control all Sun 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 software 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 disk devices. Multipathing is not supported on tape drives or libraries, or on IP over FC.

Enabling or Disabling Multipathing

Before you change multipathing configuration consider the following and then follow the instructions for your machine architecture (SPARC or x86) described in the subsequent sections.

Device Specific Considerations

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 Name Change Considerations

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

Example device name with multipath disabled:

/dev/dsk/c1t1d0s0

Example device name with multipath enabled:

/dev/dsk/c3t2000002037CD9F72d0s0

Because of this, if you have applications that directly consume device names, they must be configured to use the new names whenever you change multipath configuration from disabled to enabled or vice-versa.

The system's /etc/vfstab file and the dump configuration also contains references to device names. On SPARC based systems, the stmsboot(1M) command described in the following sections automatically updates the /etc/vfstab and the dump configuration with the new device names. On x86 based systems this must be performed manually. You need to do this only if the device names listed in /etc/vfstab or your dump device are affected by the device name changes. For updating /etc/vfstab, simply edit the file with any text editor and substitute new device names in place of old device names. Use dumpadm(1M) command to update the dump configuration.

Enabling or Disabling Multipathing on SPARC Based Systems

On SPARC based systems, you can enable or disable multipathing on FC devices using the stmsboot(1M) command. The command also updates /etc/vfstab and dump configuration to reflect devices name changes during the next reboot.

The following consideration apply (for stmsboot -e, -d, and -u options):

You should plan to reboot immediately after running the stmsboot command.

Ensure that eeprom(1M) boot-device is set to boot from your current boot device. This is needed as stmsboot command reboots the machine to complete the operation.

The stmsboot command saves a copy of your original /kernel/drv/fp.conf and /etc/vfstab files before modifying them. The saved files can be used to recover from any unexpected problems. See Appendix C, Multipathing Troubleshooting, if you encounter unexpected problems during stmsboot.

Note - The behavior of stmsboot command in the Solaris 10 differs from the stmsboot command provided by Sun StorEdge SAN Foundation software in the Solaris 8 and 9 OS. In the Solaris 8 and 9 OS, stmsboot command is used to enable or disable multipathing on the boot device only. In the Solaris 10, the command is used to enable or disable multipathing on all devices. The stmsboot(1M) is available only on SPARC based systems.

To Enable Multipathing

...