Distributed Replicated Storage Across Four Storage Nodes With GlusterFS On Fedora 12 - Page 2

3 Setting Up The GlusterFS Client

client1.example.com:

There's a GlusterFS client rpm package for Fedora 12, but the problem with it is that you will get errors like df: `/mnt/glusterfs': Software caused connection abort or df: `/mnt/glusterfs': Transport endpoint is not connected when you try to access the GlusterFS share. That's why we build the GlusterFS client from the sources to avoid these problems.

Before we build the GlusterFS client, we install its prerequisites:

yum groupinstall 'Development Tools'

yum groupinstall 'Development Libraries'

yum install libibverbs-devel fuse-devel

Then we download the GlusterFS 2.0.9 sources (please note that this is the same version that is installed on the server!) and build GlusterFS as follows:

cd /tmp
wget http://ftp.gluster.com/pub/gluster/glusterfs/2.0/LATEST/glusterfs-2.0.9.tar.gz
tar xvfz glusterfs-2.0.9.tar.gz
cd glusterfs-2.0.9
./configure

At the end of the ./configure command, you should see something like this:

[...]
GlusterFS configure summary
===========================
FUSE client        : yes
Infiniband verbs   : yes
epoll IO multiplex : yes
Berkeley-DB        : yes
libglusterfsclient : yes
argp-standalone    : no

[root@client1 glusterfs-2.0.9]#

make && make install
ldconfig

Check the GlusterFS version afterwards (should be 2.0.9):

glusterfs --version

[root@client1 glusterfs-2.0.9]# glusterfs --version
glusterfs 2.0.9 built on Feb 19 2010 19:20:46
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@client1 glusterfs-2.0.9]#

Then we create the following two directories:

mkdir /mnt/glusterfs
mkdir /etc/glusterfs

Next we create the file /etc/glusterfs/glusterfs.vol:

vi /etc/glusterfs/glusterfs.vol

volume remote1
  type protocol/client
  option transport-type tcp
  option remote-host server1.example.com
  option remote-subvolume brick
end-volume

volume remote2
  type protocol/client
  option transport-type tcp
  option remote-host server2.example.com
  option remote-subvolume brick
end-volume

volume remote3
  type protocol/client
  option transport-type tcp
  option remote-host server3.example.com
  option remote-subvolume brick
end-volume

volume remote4
  type protocol/client
  option transport-type tcp
  option remote-host server4.example.com
  option remote-subvolume brick
end-volume

volume replicate1
  type cluster/replicate
  subvolumes remote1 remote2
end-volume

volume replicate2
  type cluster/replicate
  subvolumes remote3 remote4
end-volume

volume distribute
  type cluster/distribute
  subvolumes replicate1 replicate2
end-volume

volume writebehind
  type performance/write-behind
  option window-size 1MB
  subvolumes distribute
end-volume

volume cache
  type performance/io-cache
  option cache-size 512MB
  subvolumes writebehind
end-volume

Make sure you use the correct server hostnames or IP addresses in the option remote-host lines!

That's it! Now we can mount the GlusterFS filesystem to /mnt/glusterfs with one of the following two commands:

glusterfs -f /etc/glusterfs/glusterfs.vol /mnt/glusterfs

mount -t glusterfs /etc/glusterfs/glusterfs.vol /mnt/glusterfs

You should now see the new share in the outputs of...

mount

[root@client1 ~]# mount
/dev/mapper/vg_server5-lv_root on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
/dev/sda1 on /boot type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
/etc/glusterfs/glusterfs.vol on /mnt/glusterfs type fuse.glusterfs (rw,allow_other,default_permissions,max_read=131072)
[root@client1 ~]#

... and...

df -h

[root@client1 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_server5-lv_root
                       29G  2.5G   25G  10% /
tmpfs                 185M     0  185M   0% /dev/shm
/dev/sda1             194M   23M  161M  13% /boot
/etc/glusterfs/glusterfs.vol
                       57G  9.8G   47G  17% /mnt/glusterfs
[root@client1 ~]#

(The size of the distributed storage is calculated by replication1 + replication2, where both replication volumes are as big as the smallest brick.)

Instead of mounting the GlusterFS share manually on the client, you could modify /etc/fstab so that the share gets mounted automatically when the client boots.

Open /etc/fstab and append the following line:

vi /etc/fstab

[...]
/etc/glusterfs/glusterfs.vol  /mnt/glusterfs  glusterfs  defaults  0  0

To test if your modified /etc/fstab is working, reboot the client:

reboot

After the reboot, you should find the share in the outputs of...

df -h

... and...

mount

4 Testing

Now let's create some test files on the GlusterFS share:

client1.example.com:

touch /mnt/glusterfs/test1
touch /mnt/glusterfs/test2
touch /mnt/glusterfs/test3
touch /mnt/glusterfs/test4
touch /mnt/glusterfs/test5
touch /mnt/glusterfs/test6

Now let's check the /data/export directory on server1.example.com, server2.example.com, server3.example.com, and server4.example.com. You will notice that replication1 as well as replication2 hold only a part of the files/directories that make up the GlusterFS share on the client, but the nodes that make up replication1 (server1 and server2) or replication2 (server3 and server4) contain the same files (mirroring):

server1.example.com:

ls -l /data/export

[root@server1 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test1
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test2
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test4
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test5
[root@server1 ~]#

server2.example.com:

ls -l /data/export

[root@server2 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test1
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test2
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test4
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test5
[root@server2 ~]#

server3.example.com:

ls -l /data/export

[root@server3 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test3
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test6
[root@server3 ~]#

server4.example.com:

ls -l /data/export

[root@server4 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test3
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test6
[root@server4 ~]#

Now we shut down server1.example.com and server4.example.com and add/delete some files on the GlusterFS share on client1.example.com.

server1.example.com/server4.example.com:

shutdown -h now

client1.example.com:

rm -f /mnt/glusterfs/test5
rm -f /mnt/glusterfs/test6

The changes should be visible in the /data/export directory on server2.example.com and server3.example.com:

server2.example.com:

ls -l /data/export

[root@server2 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test1
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test2
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test4
[root@server2 ~]#

server3.example.com:

ls -l /data/export

[root@server3 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test3
[root@server3 ~]#

Let's boot server1.example.com and server4.example.com again and take a look at the /data/export directory:

server1.example.com:

ls -l /data/export

[root@server1 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test1
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test2
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test4
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test5
[root@server1 ~]#

server4.example.com:

ls -l /data/export

[root@server4 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test3
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test6
[root@server4 ~]#

As you see, server1.example.com and server4.example.com haven't noticed the changes that happened while they were down. This is easy to fix, all we need to do is invoke a read command on the GlusterFS share on client1.example.com, e.g.:

client1.example.com:

ls -l /mnt/glusterfs/

[root@client1 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test1
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test2
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test3
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test4
[root@client1 ~]#

Now take a look at the /data/export directory on server1.example.com and server4.example.com again, and you should see that the changes have been replicated to these nodes:

server1.example.com:

ls -l /data/export

[root@server1 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test1
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test2
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test4
[root@server1 ~]#

server4.example.com:

ls -l /data/export

[root@server4 ~]# ls -l /data/export
total 0
-rw-r--r-- 1 root root 0 2010-02-23 15:41 test3
[root@server4 ~]#

5 Links

GlusterFS: http://www.gluster.org/
Fedora: http://fedoraproject.org/

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Distributed Replicated Storage Across Four Storage Nodes With GlusterFS On Fedora 12 - Page 2

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3 Setting Up The GlusterFS Client

4 Testing

5 Links

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