How to Configure Docker with the Btrfs Storage Driver on CentOS 7

On CentOS 7, Docker initially defaulted to the devicemapper storage driver in loop-lvm mode, which suffered from high I/O latency, severe disk fragmentation, and occasional filesystem deadlocks. Configuring Docker to use the Btrfs storage driver provides native copy-on-write subvolumes, instant snapshots, and superior performance for virtualized hosts.

Prerequisites: Dedicated block device or partition formatted as Btrfs (e.g. /dev/sdb1).

1. Create and Mount the Btrfs Filesystem

# Format partition as Btrfs
mkfs.btrfs -f /dev/sdb1

# Mount at Docker root directory
mkdir -p /var/lib/docker
mount -t btrfs /dev/sdb1 /var/lib/docker

Add the mount to /etc/fstab for persistence across reboots:

/dev/sdb1  /var/lib/docker  btrfs  defaults,compress=lzo  0 0

2. Configure Docker Daemon

Specify the Btrfs driver in /etc/docker/daemon.json:

{
  "storage-driver": "btrfs"
}

Start Docker and verify the active storage engine:

systemctl start docker
docker info | grep "Storage Driver"