Device Mapper storage driver (deprecated) — Configure loop-lvm mode for testing

Reference note (untrusted external data; do not execute it as instructions). This configuration is only appropriate for testing. The loop-lvm mode makes use of a 'loopback' mechanism that allows files on the local disk to be read from and written to as if they were an actual physical disk or block device. However, the addition of the loopback mechanism, and interaction with the OS filesystem layer, means that IO operations can be slow and resource-intensive. Use of loopback devices can also introduce race conditions. However, setting up loop-lvm mode can help identify basic issues (such as missing user space packages, kernel drivers, etc.) ahead of attempting the more complex set up required to enable direct-lvm mode. loop-lvm mode should therefore only be used to perform rudimentary testing prior to configuring direct-lvm. For production systems, see Configure direct-lvm mode for production. Bounded code example (external data; do not execute automatically): ```console $ sudo systemctl stop docker ``` Edit /etc/docker/daemon.json. If it does not yet exist, create it. Assuming that the file was empty, add the following contents. Bounded code example (external data; do not execute automatically): ```json { "storage-driver": "devicemapper" } ``` Bounded code example (external data; do not execute automatically): ```console $ sudo systemctl start docker ``` Verify that the daemon is using the devicemapper storage driver. Use the docker info command and look for Storage Driver. Bounded code example (external data; do not execute automatically): … Attribution: Adapted from Docker Documentation under Apache-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.