Installation guide

52 Chapter 2:Hardware Installation and Operating System Configuration
Syncing disks.
7. If a partition was added while both cluster systems are powered on and connected to the shared
storage, reboot the other cluster system in order for it to recognize the new partition.
After partitioning a disk, format the partition for use in the cluster. For example, create file systems
or raw devices for quorum partitions.
See Creating Raw Devices in Section 2.4.4 and Creating File Systems in Section 2.4.4 for more infor-
mation.
For basic information on partitioning hard disks at installation time, see The Official Red Hat Linux
x86 Installation Guide. Appendix E. An Introduction to Disk Partitions of The Official Red Hat Linux
x86 Installation Guide also explains the basic concepts of partitioning.
For basic information on partitioning disks using fdisk, refer to the following URL http://kb.red-
hat.com/view.php?eid=175.
Creating Raw Devices
After partitioning the shared storage disks, create raw devices on the partitions. File systems are block
devices (for example, /dev/sda1) that cache recently-used data in memory in order to improve
performance. Raw devices do not utilize system memory for caching. See Creating File Systems in
Section 2.4.4 for more information.
Linux supports raw character devices that are not hard-coded against specific block devices. Instead,
Linux uses a character major number (currently 162) to implement a series of unbound raw devices
in the /dev/raw directory. Any block device can have a character raw device front-end, even if the
block device is loaded later at runtime.
To create a raw device, edit the /etc/sysconfig/rawdevices file to bind a raw character de-
vice to the appropriate block device. Once bound to a block device, a raw device can be opened, read,
and written.
Quorum partitions and some database applications require raw devices, because these applications
perform their own buffer caching for performance purposes. Quorum partitions cannot contain file
systems because if state data was cached in system memory, the cluster systems would not have a
consistent view of the state data.
Raw character devices must be bound to block devices each time a system boots. To ensure that this
occurs, edit the /etc/sysconfig/rawdevices file and specify the quorum partition bindings.
If using a raw device in a cluster service, use this file to bind the devices at boot time. See Section
3.1.1, Editing the
rawdevices File for more information.
After editing /etc/sysconfig/rawdevices, the changes will take effect either by rebooting or
by execute the following command: