Distributed Replicated Storage Across Four Storage Nodes With GlusterFS On Fedora 12

This tutorial shows how to combine four single storage servers (running Fedora 12) to a distributed replicated storage with GlusterFS. Nodes 1 and 2 (replication1) as well as 3 and 4 (replication2) will mirror each other, and replication1 and replication2 will be combined to one larger storage server (distribution). Basically, this is RAID10 over network. If you lose one server from replication1 and one from replication2, the distributed volume continues to work. The client system (Fedora 12 as well) will be able to access the storage as if it was a local filesystem. GlusterFS is a clustered file-system capable of scaling to several peta-bytes. It aggregates various storage bricks over Infiniband RDMA or TCP/IP interconnect into one large parallel network file system. Storage bricks can be made of any commodity hardware such as x86_64 servers with SATA-II RAID and Infiniband HBA.

I do not issue any guarantee that this will work for you!

1 Preliminary Note

In this tutorial I use five systems, four servers and a client:

• server1.example.com: IP address 192.168.0.100 (server)
• server2.example.com: IP address 192.168.0.101 (server)
• server3.example.com: IP address 192.168.0.102 (server)
• server4.example.com: IP address 192.168.0.103 (server)
• client1.example.com: IP address 192.168.0.104 (client)

All five systems should be able to resolve the other systems' hostnames. If this cannot be done through DNS, you should edit the /etc/hosts file so that it contains the following lines on all five systems:

vi /etc/hosts

[...]
192.168.0.100   server1.example.com     server1
192.168.0.101   server2.example.com     server2
192.168.0.102   server3.example.com     server3
192.168.0.103   server4.example.com     server4
192.168.0.104   client1.example.com     client1
[...]

(It is also possible to use IP addresses instead of hostnames in the following setup. If you prefer to use IP addresses, you don't have to care about whether the hostnames can be resolved or not.)

2 Setting Up The GlusterFS Servers

server1.example.com/server2.example.com/server3.example.com/server4.example.com:

The GlusterFS server is available as a package for Fedora 12, therefore we can install it as follows:

yum install glusterfs-server

The command

glusterfs --version

should now show the GlusterFS version that you've just installed (2.0.9 in this case):

[root@server1 ~]# glusterfs --version
glusterfs 2.0.9 built on Jan  3 2010 00:12:49
Repository revision: v2.0.9
Copyright (c) 2006-2009 Gluster Inc. <http://www.gluster.com>
GlusterFS comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of GlusterFS under the terms of the GNU General Public License.
[root@server1 ~]#

Next we create a few directories:

mkdir /data/
mkdir /data/export
mkdir /data/export-ns

Now we create the GlusterFS server configuration file /etc/glusterfs/glusterfsd.vol (we make a backup of the original /etc/glusterfs/glusterfsd.vol file first) which defines which directory will be exported (/data/export) and what client is allowed to connect (192.168.0.101 = client1.example.com):

cp /etc/glusterfs/glusterfsd.vol /etc/glusterfs/glusterfsd.vol_orig
cat /dev/null > /etc/glusterfs/glusterfsd.vol
vi /etc/glusterfs/glusterfsd.vol

volume posix
  type storage/posix
  option directory /data/export
end-volume

volume locks
  type features/locks
  subvolumes posix
end-volume

volume brick
  type performance/io-threads
  option thread-count 8
  subvolumes locks
end-volume

volume server
  type protocol/server
  option transport-type tcp
  option auth.addr.brick.allow 192.168.0.104
  subvolumes brick
end-volume

Please note that it is possible to use wildcards for the IP addresses (like 192.168.*) and that you can specify multiple IP addresses separated by comma (e.g. 192.168.0.104,192.168.0.105).

Afterwards we create the system startup links for the GlusterFS server and start it:

chkconfig --levels 35 glusterfsd on
/etc/init.d/glusterfsd start