Helix Core Server Administrator Guide: Fundamentals (2019.1)

File systems

Filesystem performance is an important component of operating system performance. The various operating systems usually offer several filesystems, each with their own performance characteristics that can favor a particular Helix server workload. For best p4d performance, the db.* files should be located on a high-performance filesystem. In general, the XFS filesystem has good performance characteristics for most Helix server workloads. The XFS filesystem is available on several operating systems, including Linux distributions using later Linux 2.6 64-bit kernels.

Reading pages into a cache in anticipation of being requested is an optimization that is often implemented within various I/O subsystem components. This optimization is commonly known as "read-ahead". In some implementations, read-ahead can be tuned, which might result in better performance. But tuning read-ahead can be a bit of an art. For example, increasing the read-ahead size might result in better performance for operations requiring mostly sequential reads. But the same increased read-ahead size applied consistently during random reads might unnecessarily discard previously-cached data that might have satisfied subsequent requests.