How to setup GFS on RHEL/CentOS/Fedora

A clustered file system or SAN file system, is an enterprise storage file system which can be shared (concurrently accessed for reading and writing) by multiple computers. Such devices are usually clustered servers, which connect to the underlying block device over an external storage device. Such a device is commonly a storage area network (SAN).
Examples of such file systems:
* GFS : The Red Hat Global File System
* GPFS : IBM General Parallel File System
* QFS : The Sun Quick File System
* OCFS : Oracle cluster file system
In the rest of tutorial we will focus on GFS2 file system the new version of GFS file system, and how to mount a shared disk on a Fedora, Red Hat or CentOS. GFS (Global File System) is a cluster file system. It allows a cluster of computers to simultaneously use a block device that is shared between them (with FC, iSCSI, NBD, etc…). GFS is a free software, distributed under the terms of the GNU General Public License, was originally developed as part of a thesis-project at the University of Minnesota in 1997.
So, let start this brief configuration.
Install Clustering Software
Add tools for Cluster and Cluster Storage in RHN to the servers: So on both servers
[mezgani@node1 ~]$ sudo yum -y groupinstall Clustering
[mezgani@node1 ~]$ sudo yum -y groupinstall “Cluster Storage”
[mezgani@node2 ~]$ sudo yum -y groupinstall Clustering
[mezgani@node2 ~]$ sudo yum -y groupinstall “Cluster Storage”

After, on first node set admin password, activate luci and restart the service :
[mezgani@node1 ~]$ sudo luci_admin init
Initializing the luci server
Creating the ‘admin’ user
Enter password:

[mezgani@node1 ~]$ sudo chkconfig luci on
[mezgani@node1 ~]$ sudo service luci start

On both nodes, start ricci agent:
[mezgani@node1 ~]$ sudo chkconfig ricci on
[mezgani@node2 ~]$ sudo chkconfig ricci on
[mezgani@node1 ~]$ sudo service ricci start
[mezgani@node2 ~]$ sudo service ricci start

Make sure all the necessary daemons start up with the cluster..
[mezgani@node1 ~]$ sudo chkconfig gfs2 on
[mezgani@node1 ~]$ sudo chkconfig cman on
[mezgani@node1 ~]$ sudo service cman start
[mezgani@node1 ~]$ sudo service gfs2 start
[mezgani@node2 ~]$ sudo chkconfig gfs2 on
[mezgani@node2 ~]$ sudo chkconfig cman on
[mezgani@node2 ~]$ sudo service cman start
[mezgani@node2 ~]$ sudo service gfs2 start

luci is started so you can connect to https://node1:8084/ with admin user and password that you’ve set.
Create a new cluster ‘delta’ and add nodes using locally installed files option

Later, you may use parted to manage partitions on sda disk, and create some partitions.
Parted is an industrial-strength package for creating, destroying, resizing, checking and copying partitions, and the file systems on them. It support big partitions unlike fdisk.
For example here i create a partition of 1T.
[mezgani@node1 ~]$ sudo parted /dev/sda
GNU Parted 1.8.1
On utilise /dev/sda
Welcome to GNU Parted! Type ‘help’ to view a list of commands.
(parted) p

Model: HP MSA2012fc (scsi)
Disk /dev/sda: 2400GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number Start End Size File system Name Fanions
2 1001GB 2400GB 1399GB ext3 primary

(parted) mkpart primary
Type de système de fichiers? [ext2]? ext3
Début? 0
Fin? 1001GB
(parted) print

Model: HP MSA2012fc (scsi)
Disk /dev/sda: 2400GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number Start End Size File system Name Fanions
1 17,4kB 1001GB 1001GB ext3 primary
(parted) quit

After creating partition, make gfs2 file system on it, with mkfs.gfs2 like this
[mezgani@node1 ~]$ sudo /sbin/mkfs.gfs2 -p lock_dlm -t delta:gfs2 -j 8 /dev/sda1
This will destroy any data on /dev/sda1.
It appears to contain a ext3 filesystem.

Are you sure you want to proceed? [y/n] y

Device: /dev/sda1
Blocksize: 4096
Device Size 932.25 GB (244384761 blocks)
Filesystem Size: 932.25 GB (244384760 blocks)
Journals: 8
Resource Groups: 3730
Locking Protocol: “lock_dlm”
Lock Table: “delta:gfs2″

Last, make a directory on all nodes and mount our gfs file system on them.
[mezgani@node1 ~]$ sudo mkdir /home/disk
[mezgani@node2 ~]$ sudo mkdir /home/disk
[mezgani@node1 ~]$ sudo mount -o acl -t gfs2 /dev/sda1 /home/disk
[mezgani@node2 ~]$ sudo mount -o acl -t gfs2 /dev/sda1 /home/disk
….

However, if a storage device loses power or is physically disconnected, file system corruption may occur.
Well, you can recover the GFS2 file system by using the gfs_fsck command.

[mezgani@node1 ~]$ sudo fsck.gfs2 -v -y /dev/sda1
With the -y flag specified, the fsck.gfs2 command does not prompt you for an answer before making changes.