Reducing SSD Wear with systemd-tmpfiles and tmpfs

Sep 16, 2026

Most of what lands on a disk every day does not need to survive a reboot: build artifacts, package caches, browser caches, logs, temp files. Moving those to tmpfs (/tmp) keeps them in memory instead of wearing out the SSD, and directories declared via user tmpfiles.d come back automatically at login — a reboot cleans up whatever is left.

User entries live in ~/.config/user-tmpfiles.d/*.conf:

d /tmp/build/cargo 0755 - - -
D /tmp/logs/app 0755 - - -

Apply without logging out:

systemd-tmpfiles --user --create

d creates the directory if missing; D additionally empties it on boot — suitable for build trees, unsuitable for anything with cross-boot value. See the tmpfiles reference for the full type list.

Build outputs

Compilers rewrite the same files on every invocation. Point the output directory at tmpfs:

export CARGO_TARGET_DIR=/tmp/build/cargo/myproject
cargo build

Use one subdirectory per project to avoid lock contention. The same pattern works for cmake -B /tmp/build/<project>, GOCACHE=/tmp/build/go-cache, Jest --cacheDirectory, or .pytest_cache — the next build recreates everything, so losing the directory on reboot only costs a rebuild.

Package manager temp and logs

Per-operation temp and log directories are never reused across boots, so they are free to move:

d /tmp/pkg/npm-logs 0755 - - -
d /tmp/pkg/prebuilds 0755 - - -

export npm_config_cache=/tmp/pkg/npm-cache

Moving the full download cache saves writes but costs re-downloads after reboot — worth it on fast networks, otherwise move only the logs and temp extraction dirs.

Browser and app caches

Browsers update disk cache, shader and GPU cache on nearly every page load. Declare the target and symlink or point the app’s cache setting at it:

d /tmp/cache/chromium 0700 - - -
d /tmp/cache/thumbnails 0755 - - -

ln -s /tmp/cache/thumbnails ~/.cache/thumbnails

Redirect only cache subdirectories (Cache, GPUCache, ShaderCache), never the whole profile — cookies and settings stay on disk. Use 0700 for paths that may hold session tokens, since /tmp is world-readable.

Logs and crash dumps

Append-heavy logs that are almost never read are safe to redirect wholesale, with age-based cleanup bounding tmpfs usage:

d /tmp/logs/app 0755 - - 7d -

The tradeoff for all of the above: tmpfs shares RAM with applications and is empty after reboot, so keep working sets comfortably below free RAM and expect a slower first build or page load after boot.