rust-idle

Give a break to your spinning rust.

rust-idle is a small linux daemon that spin down hard drives after a period of idle time.

rust-idle is a reimplementation of Christian Mueller's hd-idle inspired by another reimplementation in go.

Why?

Yet another implementation?

Why not? Rust is well suited for this task and I couldn't let go have it all. 😏

The real reason is that this is meant as an exercise to see how well rust fares for writing simple and small system daemons that are as lean as possible. A domain where C is king.

Warning

Frequently spinning down hard drives can quickly wear down the head parking mechanism. This can potentially offset any cost saving on energy or spindle wear.

This software is provided as-is, without warranty of any kind. The authors decline all responsibility for any damage resulting from its use.

Features

• Configurable idle time period and verbosity per hard drive, default settings for all other drives,
• Possibility to sync the filesystems on the hard-drive before spinning it down and/or after it has waked up. This prevent spurious flushing of dirty pages and enables swifter idling,
• Systemd unit file included, log-level formatting for journald,
• Tiny runtime footprint: no allocations during normal operation, unless logging is enabled or new drives are hot-plugged; Small binary when built with build-std (71kB on x86_64, while the go implementation is 1.6M stripped),
• Like the go implementation, rust-idle doesn't monitors activity on root device but instead monitors partitions. This prevents false-positives when monitoring daemons like smartd or udiskd query the drive's status registers,
• ❌ Monitor and spin down disks connected over USB (planned, not yet implemented),
• ❌ Has only been tested on x86_64 linux,
• ❓ Any suggestion? Please open an [issue].

Installation

dependencies: cargo and rustc. For a smaller binary size, rustup with a nightly toolchain is recommended.

On Arch Linux, the rust-idler-git package can be built from the AUR, or with arch/PKGBUILD found in this repos.

Cargo can build this project the usual way (cargo build --release), however build.sh will try to use the build-std feature, if available.

install.sh installs the binary, service file, and documentation under PREFIX=/usr/local/ by default. To test its behavior, it is possible to run it as a normal user, with the right environment. For example:

export DESTDIR="$XDG_RUNTIME_DIR/testroot" PREFIX=/usr
./install.sh
find "$DESTDIR" -type f

/run/user/1000/testroot/etc/conf.d/rust-idle
/run/user/1000/testroot/usr/lib/systemd/system/rust-idle.service
/run/user/1000/testroot/usr/share/licenses/rust-idle/LICENSE
/run/user/1000/testroot/usr/share/doc/rust-idle/README.md
/run/user/1000/testroot/usr/bin/rust-idle

Usage

Once installed, the daemon must be enabled and started with:

# systemctl enable --now rust-idle

With the default configuration under /etc/conf.d/rust-idle, rust-idle waits for 10min of idle time before syncing and spinning down any SATA drive found on the system.

Behavior can be specialized per device. Setting an idle time of 0 disable any action. For example:

RUST_IDLE_OPTS= :0 /dev/sda:600 /dev/sdb:1200

will spin down the drive sda after 10min of idle time, sdb after 20 min, and ignore any other drive present in the system.