Nodiratime

Nodiratime is a Linux mount option that disables updating the access time (atime) for directories when they are accessed. This reduces write activity on directory inodes, which can improve performance on workloads with heavy directory traversal. File atimes remain unaffected, and the option does not change other metadata updates.

Usage of nodiratime is achieved by supplying the option to the mount command or by including it in fstab. Example: mount -t ext4 -o nodiratime /dev/sda1 /mnt/data. Alternatively, in /etc/fstab you can specify: /dev/sda1 /mnt/data ext4 defaults,nodiratime 0 2. In many distributions, relatime is the default, and nodiratime is commonly used in addition to relatime to further reduce directory write traffic.

Interaction with other atime-related options: Noatime disables all atime updates for all files, whereas nodiratime disables only directory atimes while leaving file atimes unaffected. Relatime updates atimes under a reduced set of conditions to balance performance and semantics. When using nodiratime with noatime or relatime, it is important to understand the interaction and test software that relies on atime semantics.

Caveats: Some tools and workflows rely on directory atime for scheduling or integrity checks, so nodiratime may affect such processes. If precise atime information is required, avoid using nodiratime.

History and scope: Nodiratime has been supported in the Linux kernel for many years and is commonly used on ext2/3/4 and other Linux filesystems to optimize performance in systems with frequent directory reads.