How to Create a Replicated GlusterFS Volumes

Replicated volumes replicates files across bricks in the volume. You can use replicated volumes in environments where high-availability and high-reliability are critical.

In this tutorial, we are going to create a Replicated GlusterFS Volume Across two servers. Both servers we already installed Glusterfs server packages, if you didn’t installed yet you can take a look to this article describing ” How to Install and Setup GlusterFS Server on Centos 7 / RHEL 7 and Ubuntu 16.04 LTS“, have an empty disk attached as /dev/sdb. Using this disk, we will create a new logical volume (lv01) that will be mounted for the XFS bricks.

Enviroment

Step 1./ Preparing Servers:

– Configuring /etc/hosts

– GlusterFS components use DNS for name resolutions, if you do not have a DNS on your environment then update /etc/hosts file on every server and ensure that the host names of each server are accordingly resolvable.

# sudo vi /etc/hosts

192.168.1.20  glusterfs01.yallalabs.local  glusterfs01
192.168.1.21  glusterfs02.yallalabs.local  glusterfs02
192.168.1.30 client01.yallalabs.local client

– Configuring Firewall

– By default, glusterd will listen on tcp/24007, if you have firewall running, open the port or run below command on each node to allow all connections within the cluster nodes:

# firewall-cmd --zone=public --add-rich-rule='rule family="ipv4" source address="" accept'
# firewall-cmd --reload

– Preparing Bricks

– Create the partition using the fdisk command:

# fdisk /dev/sdb
...
Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 1
....
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
....
Command (m for help): w

– Type the following command to inform the operating system kernel of creation of the new partition:

# partprobe

– Create a physical volume by using the pvcreate command:

# pvcreate /dev/sdb1
# vgcreate vg01 /dev/sdb1
# lvcreate -l 100%FREE -n lv01 vg01
# mkfs.xfs /dev/mapper/vg01-lv01

– Create a mountpoint brick directory using the following command:

# mkdir -p /gluster/bricks/brick1

– To mount the brick, we need to create an entry in /etc/fstab file :

# vi /etc/fstab
/dev/mapper/vg01-lv01    /gluster/bricks/brick1  xfs     defaults  0 0

Run the following command to mount the brick.

# mount -a 

– Run the df -Th command to verify the brick is successfully mounted:

# df -h

Step 2./ Creating GlusterFS trusted Storage Pool

– To create a trusted GlusterFS storage pool, you can run the following command in the first node:

# gluster peer probe glusterfs02
peer probe: success.

– To verify the status of your node and the gluster server pool, run the following command:

# gluster pool list
UUID                                    Hostname        State
54537353-2ec0-4f72-b719-6cd9788f4cf7    glusterfs02     Connected
26232d5d-eef3-412b-89d2-06b291a0c424    localhost       Connected

Step 3./ Creating GlusterFS Volume

– Create the directory vol01 under /gluster/bricks/brick1/ directory:

# mkdir /gluster/bricks/brick1/vol1

– Create the volume using the following command:

# gluster volume create replvol replica 2 glusterfs01:/gluster/bricks/brick1/vol1 glusterfs02:/gluster/bricks/brick1/vol1
Creation of replvol has been successful
Please start the volume to access data.

– Start the volume using the following command:

# gluster volume start replvol
Starting replvol has been successful

– To display the volume information just execute the following command:

# gluster volume info replvol

Volume Name: replvol
Type: Replicate
Volume ID: 85eb66b3-5860-4b09-8d37-78eec98b622d
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: glusterfs01:/bricks/brick1/vol1
Brick2: glusterfs02:/bricks/brick1/vol1
Options Reconfigured:
nfs.disable: on
transport.address-family: inet

 
We hope this tutorial was enough helpful. If you need more information, or have any questions, just comment below and we will be glad to assist you!
 

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