How to create a replicated GlusterFS volume

A replicated GlusterFS volume is the direct choice when a shared volume must keep serving data after one brick or server fails. Each file is stored on every brick in the replica set, so the volume creation step must pair bricks across separate failure domains rather than simply list any empty directories.

The gluster volume create command writes the volume definition into the trusted storage pool, but the volume remains inaccessible until it is started. The replica count controls how many full copies are stored, and the listed bricks form the replica set for this focused non-distributed layout.

Use dedicated brick filesystems and consistent node names before creating the volume. A two-way replica can keep serving data after one replica member is unavailable, but it has less split-brain protection than a three-way or arbiter design, so choose the replica count before client data is written.

Steps to create a replicated GlusterFS volume:

Check peer connectivity from a trusted-pool node.

$ sudo gluster peer status
Number of Peers: 1

Hostname: node2
Uuid: 0f8b8d42-8d5f-4d19-9a1f-2c1d4d7b9b10
State: Peer in Cluster (Connected)

Create the brick directory on each replica node.
```
$ sudo mkdir -p /srv/gluster/volume1/brick
```
Use an empty directory on a dedicated brick filesystem. Creating a brick on the system root filesystem can fill the operating system volume and may require unsafe force usage.

Related: How to mount a disk or partition in Linux
Create the replicated volume from separate peer nodes.
```
$ sudo gluster volume create volume1 replica 2 transport tcp node1:/srv/gluster/volume1/brick node2:/srv/gluster/volume1/brick
volume create: volume1: success: please start the volume to access data
```
Keep every brick in the replica set on a different server or failure domain. GlusterFS can reject same-peer replica layouts unless force is appended, and forcing that layout reduces fault tolerance.
Start the replicated volume.
```
$ sudo gluster volume start volume1
volume start: volume1: success
```
Related: How to start and stop a GlusterFS volume

Verify the volume type and brick layout.

$ sudo gluster volume info volume1
Volume Name: volume1
Type: Replicate
Status: Started
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: node1:/srv/gluster/volume1/brick
Brick2: node2:/srv/gluster/volume1/brick

Check that the brick processes are online.

$ sudo gluster volume status volume1
Status of volume: volume1
Gluster process                             TCP Port  RDMA Port  Online  Pid
------------------------------------------------------------------------------
Brick node1:/srv/gluster/volume1/brick      49152     0          Y       2148
Brick node2:/srv/gluster/volume1/brick      49153     0          Y       1987
Self-heal Daemon on node1                   N/A       N/A        Y       1763
Self-heal Daemon on node2                   N/A       N/A        Y       1814

Task Status of Volume volume1
------------------------------------------------------------------------------
There are no active volume tasks

Create a temporary mount point on a Linux client.
```
$ sudo mkdir -p /mnt/volume1
```
Mount the new volume from the client.
```
$ sudo mount -t glusterfs node1:/volume1 /mnt/volume1
```
Related: How to mount a GlusterFS volume in Linux
Write a smoke-test file through the client mount.
```
$ sudo touch /mnt/volume1/replica-test.txt
```

Verify the smoke-test file is visible on the mounted volume.

$ ls -l /mnt/volume1/replica-test.txt
-rw-r--r-- 1 root root 0 Jun 16 10:30 /mnt/volume1/replica-test.txt

Remove the smoke-test file after verification.
```
$ sudo rm /mnt/volume1/replica-test.txt
```
Unmount the manual client test mount.
```
$ sudo umount /mnt/volume1
```
Remove the temporary mount point.
```
$ sudo rmdir /mnt/volume1
```