> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Create Partitions and Filesystems btrfs > This guide teaches how to create, manage, and optimize Btrfs volumes on Linux, covering single-device setups to multi-disk RAID configurations. In this comprehensive guide, you’ll learn how to build, manage, and optimize Btrfs (B-tree file system) volumes on Linux. We cover everything from one-device setups to multi-disk RAID configurations, subvolumes, snapshots, and transparent compression. ## Btrfs Overview Btrfs is a modern copy-on-write (COW) filesystem designed for Linux environments with large storage needs, multiple disks, or advanced snapshot requirements. Its core capabilities include: | Feature | Description | | ------------------------------ | -------------------------------------------------------------------------------- | | Multi-device support | RAID-like layouts: `single`, `dup`, `raid0`, `raid1`, `raid5`, `raid6`, `raid10` | | Transparent compression | ZLIB, LZO, ZSTD algorithms for on-the-fly data reduction | | SSD optimizations | TRIM support, reduced fragmentation | | Snapshots & incremental backup | Create point-in-time subvolume copies for quick rollback and backup | | Online defragmentation | Defragment without unmounting | | Subvolumes with quotas | Isolate datasets, enforce per-subvolume space limits | | Deduplication | Post-process or realtime block dedupe | When modifying data, COW filesystems write new data to free space, update metadata, then discard the old blocks. This preserves data integrity across crashes. ![The image explains the difference between traditional filesystems and copy-on-write filesystems, highlighting how new data is written and managed. Traditional filesystems overwrite old data directly, while copy-on-write filesystems write new data to free space and update metadata before removing old data.](https://kodekloud.com/kk-media/image/upload/v1752881380/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-Create-Partitions-and-Filesystems-btrfs/filesystems-traditional-vs-copy-on-write.jpg) ## 1. Creating a Btrfs Filesystem ### 1.1 Single-Device Setup Initialize a simple Btrfs volume on `/dev/sdb1`: ```bash theme={null} sudo mkfs.btrfs /dev/sdb1 ``` Add a human-readable label: ```bash theme={null} sudo mkfs.btrfs -L "New Disk" /dev/sdb1 ``` Changing labels on a mounted filesystem can cause mount failures. Always unmount before relabeling. ### 1.2 Multi-Device & RAID Profiles Expand a Btrfs pool across `/dev/sdb` and `/dev/sdc`: ```bash theme={null} sudo mkfs.btrfs \ -d raid1 \ -m raid1 \ -L "MirrorPool" \ /dev/sdb /dev/sdc ``` | Profile | Data Layout | Use Case | | ------- | ------------- | --------------------------------- | | single | No redundancy | Tests, single-disk volumes | | dup | Metadata only | Protect metadata on single device | | raid0 | Striping | Max performance, no redundancy | | raid1 | Mirroring | Redundancy, small pools | | raid5/6 | Parity | Large pools, high capacity | | raid10 | Stripe+Mirror | Performance + redundancy | ## 2. Subvolumes Subvolumes are independent namespaces within a Btrfs filesystem—each with its own snapshots and quotas. 1. Mount the main volume: ```bash theme={null} sudo mount /dev/sdb1 /mnt/disk ``` 2. Create a subvolume named `BKP`: ```bash theme={null} sudo btrfs subvolume create /mnt/disk/BKP ``` 3. Verify the listing: ```bash theme={null} ls -lh /mnt/disk/ # drwxr-xr-x 1 root root 0 Jul 13 17:35 BKP # drwxrwxr-x 1 carol carol 988 Jul 13 17:30 Images ``` 4. Inspect subvolume metadata: ```bash theme={null} sudo btrfs subvolume show /mnt/disk/BKP # Name: BKP # UUID: e90a14fe-69fa-da4f-9764-3384f66fa32e # Subvolume ID: 260 # Creation time: 2019-07-13 17:35:40 -0300 ``` ## 3. Mounting a Specific Subvolume To mount `BKP` directly: ```bash theme={null} sudo mount -t btrfs \ -o subvol=BKP \ /dev/sdb1 /mnt/BKP ``` ## 4. Snapshots Snapshots capture a subvolume’s state at a specific point in time. They are instant, space-efficient, and independent from ongoing changes. ### 4.1 Create a Read-Write Snapshot ```bash theme={null} sudo btrfs subvolume snapshot /mnt/disk /mnt/disk/snap ``` ### 4.2 Verify & Test Remove some files from the live subvolume: ```bash theme={null} rm /mnt/disk/LG-G8S-ThinQ-* ``` Original data remains intact in the snapshot: ```bash theme={null} ls -lh /mnt/disk/snap/ # -rw-rw-r-- 1 carol carol 118K Jul 11 16:36 Twitter_Down_20190711.jpg # -rw-rw-r-- 1 carol carol 324K Jul 2 15:22 Xiaomi_Mimoji.png ``` ### 4.3 Read-Only Snapshots Immutable snapshots prevent accidental writes: ```bash theme={null} sudo btrfs subvolume snapshot -r /mnt/disk /mnt/disk/snap-ro ``` ## 5. Transparent Compression Enable compression at mount time to reduce disk usage without manual compression commands. ```bash theme={null} sudo mount -o compression=zstd /dev/sdb1 /mnt/disk ``` | Algorithm | Speed | Compression Ratio | | --------- | -------- | ----------------- | | zlib | Moderate | Good (default) | | lzo | Fast | Lower | | zstd | Fastest | Similar to zlib | ![The image lists three compression algorithms: ZLIB (default), LZO (faster but lower compression ratio), and ZSTD (faster with a similar compression ratio to ZLIB).](https://kodekloud.com/kk-media/image/upload/v1752881380/notes-assets/images/Linux-Professional-Institute-LPIC-1-Exam-101-Create-Partitions-and-Filesystems-btrfs/compression-algorithms-zlib-lzo-zstd.jpg) ## Additional Resources * [Btrfs Wiki](https://btrfs.wiki.kernel.org/) * [Kernel Documentation – Btrfs](https://www.kernel.org/doc/html/latest/filesystems/btrfs.html) * [Linux Man Pages – btrfs](https://man7.org/linux/man-pages/man5/btrfs.5.html)