The "how" consists mostly of reasonably up-to-date kernels that track main line as much as possible. As far as why, https://code.fb.com/open-source/linux/ http

The "how" consists mostly of reasonably up-to-date kernels that track main line as much as possible. As far as why, https://code.fb.com/open-source/linux/ https://code.fb.com/open-source/linux/ has a nice quote: "Btrfs has played a role in increasing efficiency and resource utilization in Facebook’s data centers in a number of different applications. Recently, Btrfs helped eliminate priority inversions caused by the journaling behavior of the previous filesystem, when used for I/O control with cgroup2 (described below). Btrfs is the only filesystem implementation that currently works with resource isolation, and it’s now deployed on millions of servers, driving significant efficiency gains."