iomark

A CrystalDiskMark-style disk benchmark for the terminal.
One static binary — fio embedded as the measurement engine, a btop-style TUI on top.

Features

• One binary, no dependencies — fio is statically linked in; nothing is extracted or installed at runtime.
• CrystalDiskMark semantics — same default workloads (the CDM 9 "NVMe SSD" preset), same scoring (best of N runs), decimal MB/s. Each task measures read then write before moving to the next.
• Live TUI — big numbers over proportional bars, updating in real time. K flips between MB/s and IOPS (the IOPS view also shows mean latency per cell), Q quits.
• Scriptable — --json emits one NDJSON object per completed workload; non-TTY output degrades to plain lines for CI logs.

Install

macOS · Linux

Installs into ~/.local/bin (works in Git Bash and MSYS2 on Windows too):

curl -fsSL https://iomark.dev | sh

Windows

Installs into %LOCALAPPDATA%\Programs\iomark and adds it to your user PATH:

irm https://iomark.dev/install.ps1 | iex

Run once, install nothing

quick downloads to a temp directory, runs the benchmark and deletes the binary again:

curl -fsSL https://iomark.dev | sh -s -- quick            # current directory
curl -fsSL https://iomark.dev | sh -s -- quick /mnt/data  # a specific disk

& ([scriptblock]::Create((irm https://iomark.dev/install.ps1))) quick D:

The installer verifies the download against the release's SHA256SUMS. --version <tag> pins a release, --dir <path> picks the install directory, and uninstall removes the binary again. Prebuilt archives for every platform are also on the releases page.

Usage

iomark                     # benchmark the current directory's disk
iomark /path/to/mount      # benchmark a specific disk
iomark --json > out.ndjson # machine-readable results

Option	Description	Default
<TARGET_DIR>	Directory to benchmark (the test file is created there)	.
--tasks <LIST>	Comma-separated workloads: (SEQ|RND)<block>Q<depth>T<threads>	CDM 9 preset
--type <UNIT>	Initial display unit, MB/s or IOPS (K toggles in the TUI)	MB/s
--runs <N>	Measured runs per operation, best kept	3
--size <SIZE>	Test file size, binary units	1GiB
--duration <TIME>	Duration of each measured run	5s
--warmup <TIME>	Unmeasured warmup per operation (0s disables)	5s
--interval <TIME>	Pause between operations (0s disables)	5s
--color <MODE>	auto, truecolor, 256, ansi or never	auto
--json	NDJSON output, one object per workload	off
-V, --version	Print version (iomark + embedded fio)

The default task list is CrystalDiskMark 9's "NVMe SSD" preset, SEQ1MQ8T1,SEQ128KQ32T1,RND4KQ32T16,RND4KQ1T1. Custom workloads follow the same grammar: RND8KQ4T4 is random 8 KiB blocks at queue depth 4 with 4 threads.

Building

git clone --recurse-submodules https://github.com/feeeei/iomark
cd iomark
cargo build --release

Requirements: Rust 1.89+, make, a C compiler, sh.

Platform	Notes
Linux (x86_64 / ARM64)	libaio-dev and zlib1g-dev recommended
macOS (Apple Silicon / Intel)	works out of the box
Windows x86_64	build inside an MSYS2 MINGW64 shell with the x86_64-pc-windows-gnu toolchain
Windows ARM64	experimental: MSYS2 CLANGARM64 + aarch64-pc-windows-gnullvm

Methodology

Tasks run in order; each task measures read first, then write (CDM instead runs every read before any write — a deliberate difference). Each operation runs one unscored warmup pass, then N scored runs of fixed duration (--time_based); the best bandwidth and the lowest mean latency are reported, exactly like CrystalDiskMark. The shared test file is written full of data up front (no sparse-file shortcuts) and deleted on exit — including on Ctrl-C.

Per-platform fio engines: libaio (Linux), posixaio (macOS), windowsaio (Windows), always with direct=1.

Comparability notes

• MB/s is decimal (bytes ÷ 10⁶), matching CDM. IOPS and latency come from fio's job statistics.
• On macOS there is no O_DIRECT; fio's direct=1 maps to F_NOCACHE, which is a weaker cache bypass. macOS numbers are comparable to other macOS tools (AmorphousDiskMark), not bit-for-bit to Linux/Windows.
• macOS also caps in-flight POSIX AIO per process (kern.aioprocmax, default 16), so Q32 workloads effectively run at a shallower queue depth there; iomark prints a warning when a task exceeds the limit. The caps can be raised until reboot (sudo sysctl kern.aioprocmax=256 kern.aiomax=1024), but gains are modest: the kernel services POSIX AIO through a small worker-thread pool (kern.aiothreads, default 4).
• CDM drives Windows' DiskSpd; iomark drives fio everywhere. Numbers on the same hardware land close to CDM's but are not guaranteed identical.

License

GPL-2.0-only — iomark statically links fio, which is GPL-2.0. See LICENSE.