Installation guide

completely rather than attempting a clean shutdown (for example, shutdown -h now). 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 chkconfig management and verify that the node turns off immediately
when fenced. T he preferred way to disable ACPI Soft-Off is with chkconfig 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=off to the kernel boot command line of the /boot/grub/grub.conf file
Important
This method completely disables ACPI; some computers do not boot correctly if ACPI is
completely disabled. Use this method only if the other methods are not effective for your
cluster.
The following sections provide procedures for the preferred method and alternate methods of disabling
ACPI Soft-Off:
Section 2.3.1, “Disabling ACPI Soft-Off with chkconfig Management” — Preferred method
Section 2.3.2, “Disabling ACPI Soft-Off with the BIOS” — First alternate method
Section 2.3.3, “Disabling ACPI Completely in the grub.conf File” — Second alternate method
2.3.1. Disabling ACPI Soft-Off with chkconfig Management
You can use chkconfig management to disable ACPI Soft-Off either by removing the ACPI daemon
(acpid) from chkconfig management or by turning off acpid.
Chapter 2. Before Configuring a Red Hat Cluster
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