Installation guide

For more complete information on the parameters you can configure with the

/etc/sysco nfi g /l uci file, refer to the documentation within the file itself.

2.5. Configuring ACPI For Use wit h Int egrat ed Fence Devices

If your cluster uses integrated fence devices, you must configure ACPI (Advanced Configuration and

Power Interface) to ensure immediate and complete fencing.

Note

For the most current information about integrated fence devices supported by Red Hat High

Availability Add-On, refer to http://www.redhat.com/cluster_suite/hardware/.

If a cluster node is configured to be fenced by an integrated fence device, disable ACPI Soft-Off for

that node. Disabling ACPI Soft-Off allows an integrated fence device to turn off a node immediately

and completely rather than attempting a clean shutdown (for example, shutdo wn -h no w).

Otherwise, if ACPI Soft-Off is enabled, an integrated fence device can take four or more seconds to

turn off a node (refer to note that follows). In addition, if ACPI Soft-Off is enabled and a node panics

or freezes during shutdown, an integrated fence device may not be able to turn off the node. Under

those circumstances, fencing is delayed or unsuccessful. Consequently, when a node is fenced with

an integrated fence device and ACPI Soft-Off is enabled, a cluster recovers slowly or requires

administrative intervention to recover.

Note

The amount of time required to fence a node depends on the integrated fence device used.

Some integrated fence devices perform the equivalent of pressing and holding the power

button; therefore, the fence device turns off the node in four to five seconds. Other integrated

fence devices perform the equivalent of pressing the power button momentarily, relying on the

operating system to turn off the node; therefore, the fence device turns off the node in a time

span much longer than four to five seconds.

To disable ACPI Soft-Off, use chkco nfi g management and verify that the node turns off immediately

when fenced. The preferred way to disable ACPI Soft-Off is with chkconfi g management: however, if

that method is not satisfactory for your cluster, you can disable ACPI Soft-Off with one of the

following alternate methods:

Changing the BIOS setting to "instant-off" or an equivalent setting that turns off the node without

delay

Note

Disabling ACPI Soft-Off with the BIOS may not be possible with some computers.

Appending acpi = o ff to the kernel boot command line of the /boo t/g rub/g rub. co nf file

⁠Chapt er 2 . Before Configuring t he Red Hat High Availabilit y Add- O n