Chapter 25. Extending a Stratis volume with additional block devices

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You can attach additional block devices to a Stratis pool to provide more storage capacity for Stratis file systems.

25.1. Components of a Stratis volume

Learn about the components that comprise a Stratis volume.

Externally, Stratis presents the following volume components in the command-line interface and the API:

Block devices, such as a disk or a disk partition.

Composed of one or more block devices.

A pool has a fixed total size, equal to the size of the block devices.

The pool contains most Stratis layers, such as the non-volatile data cache using the dm-cache target.

Stratis creates a /dev/stratis/my-pool/ directory for each pool. This directory contains links to devices that represent Stratis file systems in the pool.


Each pool can contain one or more file systems, which store files.

File systems are thinly provisioned and do not have a fixed total size. The actual size of a file system grows with the data stored on it. If the size of the data approaches the virtual size of the file system, Stratis grows the thin volume and the file system automatically.

The file systems are formatted with XFS.


Stratis tracks information about file systems created using Stratis that XFS is not aware of, and changes made using XFS do not automatically create updates in Stratis. Users must not reformat or reconfigure XFS file systems that are managed by Stratis.

Stratis creates links to file systems at the /dev/stratis/my-pool/my-fs path.


Stratis uses many Device Mapper devices, which show up in dmsetup listings and the /proc/partitions file. Similarly, the lsblk command output reflects the internal workings and layers of Stratis.

25.2. Adding block devices to a Stratis pool

This procedure adds one or more block devices to a Stratis pool to be usable by Stratis file systems.


  • Stratis is installed. See Installing Stratis.
  • The stratisd service is running.
  • The block devices that you are adding to the Stratis pool are not in use and not mounted.
  • The block devices that you are adding to the Stratis pool are at least 1 GiB in size each.


  • To add one or more block devices to the pool, use:

    # stratis pool add-data my-pool device-1 device-2 device-n

Additional resources

  • stratis(8) man page

25.3. Additional resources

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