Cheap VPS & Xen Server


Residential Proxy Network - Hourly & Monthly Packages

Striping Across Four Storage Nodes With GlusterFS On Ubuntu 9.10


This tutorial shows how to do data striping (segmentation of logically sequential data, such as a single file, so that segments can be assigned to multiple physical devices in a round-robin fashion and thus written concurrently) across four single storage servers (running Ubuntu 9.10) with GlusterFS. The client system (Ubuntu 9.10 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.

Please note that this kind of storage doesn’t provide any high-availability/fault tolerance features, as would be the case with replicated storage.

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)

Because we will run all the steps from this tutorial with root privileges, we can either prepend all commands in this tutorial with the string sudo, or we become root right now by typing

sudo su

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 looks as follows on all five systems:

vi /etc/hosts

127.0.0.1       localhost.localdomain   localhost
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

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

(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:

GlusterFS is available as a package for Ubuntu 9.10, therefore we can install it as follows:

aptitude install glusterfs-server

The command

glusterfs –version

should now show the GlusterFS version that you’ve just installed (2.0.2 in this case):

root@server1:~# glusterfs –version
glusterfs 2.0.2 built on Jun 29 2009 23:49:59
Repository revision: 07019da2e16534d527215a91904298ede09bb798
Copyright (c) 2006-2009 Z RESEARCH Inc. <http://www.zresearch.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 (192.168.0.104 = 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/server
  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 start the GlusterFS server:

/etc/init.d/glusterfs-server start

3 Setting Up The GlusterFS Client

client1.example.com:

On the client, we can install the GlusterFS client as follows:

aptitude install glusterfs-client glusterfs-server

Then we create the following directory:

mkdir /mnt/glusterfs

Next we create the file /etc/glusterfs/glusterfs.vol (we make a backup of the original /etc/glusterfs/glusterfs.vol file first):

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

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

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

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

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

volume stripe
  type cluster/stripe
  option block-size 1MB
  subvolumes remote1 remote2 remote3 remote4
end-volume

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

or

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/client1-root on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
none on /dev/shm type tmpfs (rw,nosuid,nodev)
none on /var/run type tmpfs (rw,nosuid,mode=0755)
none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
/dev/sda5 on /boot type ext2 (rw)
/etc/glusterfs/glusterfs.vol on /mnt/glusterfs type fuse.glusterfs (rw,max_read=131072,allow_other,default_permissions)
root@client1:~#

… and…

df -h

root@client1:~# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/client1-root
29G  808M   27G   3% /
udev                  122M  152K  121M   1% /dev
none                  122M     0  122M   0% /dev/shm
none                  122M   36K  122M   1% /var/run
none                  122M     0  122M   0% /var/lock
none                  122M     0  122M   0% /lib/init/rw
/dev/sda5             228M   15M  202M   7% /boot
/etc/glusterfs/glusterfs.vol
103G  3.2G   95G   4% /mnt/glusterfs
root@client1:~#

(server1.example.com, server2.example.com, server3.example.com, and server4.example.com each have about 26GB of space for the GlusterFS filesystem, so that the resulting share has a size of about 4 x 26GB (103GB).)

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 a big test file on the GlusterFS share:

client1.example.com:

dd if=/dev/zero of=/mnt/glusterfs/test.img bs=1024k count=1000

ls -l /mnt/glusterfs

root@client1:~# ls -l /mnt/glusterfs
total 1024032
-rw-r–r– 1 root root 1048576000 2009-12-22 17:31 test.img
root@client1:~#

Now let’s check the /data/export directory on server1.example.com, server2.example.com, server3.example.com, and server4.example.com. You should see the test.img file on each node, but with different sizes (due to data striping):

server1.example.com:

ls -l /data/export

root@server1:~# ls -l /data/export
total 256008
-rw-r–r– 1 root root 1045430272 2009-12-22 17:31 test.img
root@server1:~#

server2.example.com:

ls -l /data/export

root@server2:~# ls -l /data/export
total 256008
-rw-r–r– 1 root root 1046478848 2009-12-22 17:27 test.img
root@server2:~#

server3.example.com:

ls -l /data/export

root@server3:~# ls -l /data/export
total 256008
-rw-r–r– 1 root root 1047527424 2009-12-22 17:26 test.img
root@server3:~#

server4.example.com:

ls -l /data/export

root@server4:~# ls -l /data/export
total 256008
-rw-r–r– 1 root root 1048576000 2009-12-22 17:30 test.img
root@server4:~#

 

  • GlusterFS: http://www.gluster.org/
  • Ubuntu: http://www.ubuntu.com/

 

Comments

comments