DiskWatch

Single-host disk diagnostics in your terminal. The terminal you open when the disk light won't stop blinking — before you reach for iostat, iotop, smartctl, lsblk, df, du, and a panic.

Sibling to NetWatch and SysWatch. Same chrome. Same palette. Eight tabs covering every disk on one box.

What it shows

Where lsblk shows you which disks exist, DiskWatch shows you what's happening on them — capacity trending, IO throughput, p99 latency, SMART health, and the files being written right now — and tells you why in plain English when something's anomalous.

Lite

diskwatch --lite

One screen at 80×24, six keys, no tabs. Read and write throughput, a capacity line that answers how long have I got rather than how full am I, and the busiest files — sized to run in a tmux split or an SSH session to a NAS.

diskwatch  nas-01 · 4 devices                              ● 2.6 / 3.8 TB

r 128 MB/s read                              peak 412 MB/s  avg 96 MB/s
▁▂▃▅█▇▅▃▂▁▁▂▄▆█▇▄▂▁▁▁▂▃▅▇█▆▄▂▁▁▁▂▃▄▆█▇▅▃▂▁▁▂▃▅▇█▆▄▂▁▁▁▂▃▄▅▇█▆▄▂▁▁▂▃▄▆▇█▅▃▂▁▁▂
w 14 MB/s write                                    peak 38 MB/s  avg 11 MB/s
▁▁▂▁▁▂▃▂▁▁▁▂▁▁▂▂▁▁▁▂▃▂▁▁▁▁▂▁▁▂▂▁▁▁▂▁▁▁▂▂▁▁▁▂▃▂▁▁▁▂▁▁▂▂▁▁▁▂▁▁▂▃▂▁▁▁▂▁▁▂▂▁▁▂▁▁▂
 78s ago ─────────────────────────────────────────────────────────── now
/ 68%   /var 94%   health 4/4   growth +8.2 GB/day    /var 94% · 11 days left

It is not the full tool with tabs hidden — it is a different view for one machine and one question. Toggle either direction at runtime with L; the full 8-tab TUI stays the default at every terminal size. Below 80×24 Lite shows a notice rather than a clipped grid.

Same grid, keys and palette as netwatch --lite — only the subject changes.

The capacity projection needs about a minute of observation before it will commit to a number, and stays silent when usage is flat or shrinking. The file table reports events, not bytes: FSEvents and inotify say that a path changed, not who wrote it or how much (see What's real, what's deferred).

Install

brew install diskwatch                # macOS / Linux
nix-shell -p diskwatch                # NixOS / Nix
paru -S diskwatch                     # Arch
cargo install diskwatch               # anywhere with Rust

Or grab a pre-built binary from Releases.

The Nix and Arch packages are maintained by community packagers — thank you. File packaging issues with them; file diskwatch bugs here. The Repology page shows which packages are current.

git clone https://github.com/matthart1983/diskwatch.git && cd diskwatch
cargo build --release
./target/release/diskwatch

Prerequisites: Rust 1.75+ (only if building from source). No system dependencies on Linux. macOS calls the standard ioreg, diskutil, and system_profiler binaries — all preinstalled. Optional: smartmontools (brew install smartmontools / apt install smartmontools) for full SMART attribute tables — without it, the SMART tab falls back to the basic verified/failing flag from diskutil.

Keys

Themes

Seven built-in themes, matching syswatch's set and cycle order:

dark (default) · light · ocean · solarized · dracula · nord · terminal

terminal pins no colors of its own — every slot resolves to an ANSI palette entry, and foreground and background use your terminal's own defaults. If you theme your whole desktop with pywal, matugen, or a terminal profile, this is the one that follows along.

Switch it live from the settings overlay (, → Theme → Space), or start with it:

diskwatch --theme terminal      # also accepts: system, ansi

The choice isn't persisted between runs — like the other settings, it resets to dark on restart. Use the flag to make it stick.

Graph style

Every chart in the app — the Overview aggregate, the IO tab's per-device panels, and both Lite charts — draws through one renderer, so a single setting changes them all.

diskwatch --graph dots                 # btop-style braille (also: braille, btop)
diskwatch --graph dots --graph-fade    # ...plus btop's gradient and dot grid

bars is the stacked eighth-block look diskwatch shipped with — eight levels per row. dots packs four braille pixel rows into each cell, so a one-row sparkline resolves four distinct heights instead of reading as on/off. On the tall charts the difference is subtler; on Lite's 9-column row sparklines it's the difference between a shape and a blob.

--graph-fade is btop's other half: each chart runs bright at now and dims toward the left edge, over a faint dot grid. It's a separate switch because the gradient reads fine under bars too — and because it interpolates in RGB, so it's ignored under --theme terminal, which exists precisely to pin no RGB. The grid only draws on charts at least 16×4, which means the IO and Overview panels get it and Lite's 3- and 2-row charts don't.

Both are live in the settings overlay (, → Graph style / Graph fade → Space). Lite has no settings overlay of its own — press L, change it, press L back.

Tabs in detail

[1] Overview — 5 KPI tiles (capacity, IO, p99 latency, health, insights), per-device summary, aggregate IO sparkline, top insights, segmented capacity bar.

[2] Devices — block-device table with model, firmware, serial, used %, SMART status. Detail panel for the selected device.

[3] Volumes — APFS containers (macOS) with nested volumes, role, mount, FileVault. mdraid arrays (Linux) with members, slot state [UUUU], resync/recovery progress.

[4] FS — mounted filesystems with inline usage bars, threshold colors, system/user/removable classification.

[5] IO — per-device read / write throughput, 48s sparkline, p50 + p99 latency (read and write) over a 60s rolling window.

[6] SMART — full NVMe / ATA attribute tables when smartctl is on PATH; degraded banner with install instructions when not. Always shows the basic verified/failing flag.

[7] Hot Files — paths by event rate via FSEvents (macOS) / inotify (Linux). Honest footer: this tab can't show bytes/sec or process attribution without root (fs_usage) / Endpoint Security entitlement / eBPF biosnoop.

[8] Insights — anomaly cards over the collected state: capacity warnings, SMART failures, NVMe wear, drive temperature, p99 latency outliers, IO-dominant devices, hot-file runaway, removable drives.

What's real, what's deferred

Design

Inherits the *Watch family chrome — #0c1418 background, terminal-green accent, JetBrains Mono, 130×36 character grid with responsive reflow ≥ 110×30. The same character-grid mockups that drive NetWatch and SysWatch drive DiskWatch.

Anti-goals

• Not multi-host. Use NetWatch Cloud if you need a fleet view.
• Not a daemon. No long-running collector, no persisted DB.
• Not a deduper / cleaner. We surface what's eating disk; we don't delete anything. Mutation is a different tool.
• Not a backup product. Snapshots are observed, not authored.
• Not a benchmark. We measure what's happening, not what's possible.

License

MIT.