Install guide

Warning

GFS volumes can be grown if the file system requires more capacity. T he gfs_grow command is

used to expand the file system, once the LUN has been expanded. By keeping the filesystem

mapping to single LUNs, it reduces an errors (or bugs) that might arise during gfs_grow

operations. T here is no performance difference between using the DDM inode, or subsequent

CLVMD created logical volumes, built on these inodes. However, it must be stressed that you

should perform a backup of your data before attempting this command as there is a potential to

render you data unusable.

4.3.1. GFS File System Creation

For RAC, the file system must be created with arguments that are specific to the locking mechanism

(always DLM), and the name of the cluster (HA585, in our case).

$ sudo gfs_mkfs -r 512 -j 4 -p lock_dlm -t rac585:gg /dev/mapper/ohome

$ sudo gfs_mkfs-j 4 -p lock_dl m -t rac585:gg /dev/mapper/db

Oracle manages data files with transaction redo logs, and with Oracle configuration in AIO/DIO mode, the

writes always go to disk. The default journal is usually sufficient. T he increased size of resource groups

for GFS file systems is recommended for ORACLE_HOME, where the $OH/diag directory can contain

thousands of trace files, spanning tens of GBs.

Note

Oracle Clusterware HOME is not supported on GFS clustered volumes at this time. For most

installations, this will not be an imposition. There are several advantages (including, async rolling

upgrades) to placing ORA_CRS_HOME on the node’s local file system, and most customers follow

this practice.

4.3.2. /etc/fstab Entries

/dev/mapper/ohome /mnt/ohom e gfs _netdev 0 0

/dev/mapper/db /mnt/db gfs _netdev 0 0

The _netdev mount option is also useful as it ensures the file systems are unmounted before cluster

services shut down.

4.3.3. Context Dependent Pathnames (CDPN)

When ORACLE_HOME ($OH) is located on a GFS clustered volume, certain directories need to appear

the same to each node (including names of files, such as listener.ora), but have node-specific

contents.

To enable CDPN for $OH/network/admin, perform the following steps.

1. Change to the OH/network directory:

$ cd $OH/network

Chapter 4. RAC/GFS Cluster Configuration