Installation guide

5.3.3.1 LVM Configuration
The LVM configuration file /etc/lvm/lvm.conf must be modified to enable the use of CLVM.
1. By default, the LVM commands scan all devices found directly in the /dev path. This is
insufficient in dm-multipath configurations.
There are two ways to enable multipath devices for LVM. The easiest is to modify the
scan array in the configuration file as follows:
scan = [ "/dev/mapper", "/dev/cciss" ]
2. All changes to logical volumes and their states are communicated using locks. LVM
defaults to local file based locking and needs to instead use built-in cluster wide
locking. LVM commands are instructed to communicate with the CLVM daemon
(clvmd) by the following setting in the global section of the configuration file:
locking_type = 3
which is normally set accordingly when the cluster is created and the option to use
shared storage is selected.
Please reference the LVM Administrators Guide for more detailed information on using LVM
in a cluster.
5.3.3.2 Volume Configuration
In this configuration, several storage LUNs were defined to store application data. Each LUN
in used for one logical volume group and one logical volume. The following steps were
performed to create the clustered logical volume /dev/vg_sap700_gfs/lv_ci
# pvcreate /dev/mapper/DGC_017p1
# vgcreate -cy vg_sap700_gfs /dev/mapper/DGC_017p1
# lvcreate -n lv_ci -L 4G vg_sap700_gfs
# vgchange -ay g_sap700_gfs
5.3.4 GFS
In Red Hat Enterprise Linux 5.3, two versions of the GFS file systems (GFS and GFS2) are
available and supported for production use. This document describes the use of GFS.
5.3.4.1 Formatting
To format a storage volume with GFS, the helper tool gfs_mkfs must be used. The following
options must be defined:
1. -j number: number of journals. At least one journal (per machine that will mount the file
system) is required.
2. -t locktable: The lock table field. Its clustername:fsname. Clustername must match
that in cluster.conf; only members of this cluster are permitted to use this file system.
Fsname is a unique file system name used to distinguish this GFS file system from
others.
3. -p lockproto: The locking protocol that should be used. Use the DLM locking
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