3.5. Configuring ACPI For Use with Integrated Fence Devices If your cluster uses integrated fence devices, you must configure ACPI (Advanced Configuration and Power Interface) to ensure immediate and complete fencing. 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, 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, changing the BIOS setting to "instant-off" or an equivalent setting that turns off the node without delay, as described in Section 3.5.1, "Disabling ACPI Soft-Off with the BIOS" . This is the preferred method. Disabling ACPI Soft-Off with the BIOS may not be possible with some systems, however. If disabling ACPI Soft-Off with the BIOS is not satisfactory for your cluster, you can disable ACPI Soft-Off with one of the following alternate methods: Use chkconfig management and verify that the node turns off immediately when fenced, as described in Section 3.5.2, "Disabling ACPI Soft-Off with chkconfig Management" . This is the first alternate method. Appending acpi=off to the kernel boot command line of the /boot/grub/grub.conf file, as described in Section 3.5.3, "Disabling ACPI Completely in the grub.conf File" . This is the second alternate method. 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. 3.5.1. Disabling ACPI Soft-Off with the BIOS You can disable ACPI Soft-Off by configuring the BIOS of each cluster node with the following procedure. Note The procedure for disabling ACPI Soft-Off with the BIOS may differ among server systems. You should verify this procedure with your hardware documentation. You can disable ACPI Soft-Off by configuring the BIOS of each cluster node as follows: Reboot the node and start the BIOS CMOS Setup Utility program. Navigate to the Power menu (or equivalent power management menu). At the Power menu, set the Soft-Off by PWR-BTTN function (or equivalent) to Instant-Off (or the equivalent setting that turns off the node by means of the power button without delay). Example 3.1, " BIOS CMOS Setup Utility : Soft-Off by PWR-BTTN set to Instant-Off " shows a Power menu with ACPI Function set to Enabled and Soft-Off by PWR-BTTN set to Instant-Off . Note The equivalents to ACPI Function , Soft-Off by PWR-BTTN , and Instant-Off may vary among computers. However, the objective of this procedure is to configure the BIOS so that the computer is turned off by means of the power button without delay. Exit the BIOS CMOS Setup Utility program, saving the BIOS configuration. When the cluster is configured and running, verify that the node turns off immediately when fenced. Note You can fence the node with the fence_node command or Conga . Example 3.1. BIOS CMOS Setup Utility : Soft-Off by PWR-BTTN set to Instant-Off This example shows ACPI Function set to Enabled , and Soft-Off by PWR-BTTN set to Instant-Off .

Commands:
+---------------------------------------------|-------------------+ | ACPI Function [Enabled] | Item Help | | ACPI Suspend Type [S1(POS)] |-------------------| | x Run VGABIOS if S3 Resume Auto | Menu Level * | | Suspend Mode [Disabled] | | | HDD Power Down [Disabled] | | | Soft-Off by PWR-BTTN [Instant-Off | | | CPU THRM-Throttling [50.0%] | | | Wake-Up by PCI card [Enabled] | | | Power On by Ring [Enabled] | | | Wake Up On LAN [Enabled] | | | x USB KB Wake-Up From S3 Disabled | | | Resume by Alarm [Disabled] | | | x Date(of Month) Alarm 0 | | | x Time(hh:mm:ss) Alarm 0 : 0 : | | | POWER ON Function [BUTTON ONLY | | | x KB Power ON Password Enter | | | x Hot Key Power ON Ctrl-F1 | | | | | | | | +---------------------------------------------|-------------------+