_{crafted with stubborn curiosity by Bongbetic}

Fenris 🐺 — Your SSD's Tell-All Diary

Your NVMe drive has been keeping secrets. Fenris makes it confess — in real time.
How much did you write today? How long until it taps out? No fairy dust — just your actual bytes.

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Fenris is a tiny, stubborn daemon that eavesdrops on your NVMe drive's SMART gossip, writes it down every few minutes, and serves you a live dashboard that actually means something. Not "vibes" — real GB written in the last 24 hours, real GB/hour, and a real countdown in hours, days, and years until your drive's endurance runs out.

Think of it as a Fitbit for your SSD. Except it doesn't nag you to drink water.

What it actually does (no hand-waving)

• Listens — polls smartctl -j on your NVMe device (default every 5 minutes, you pick).
• Remembers — appends every sample to data/history.jsonl and rolls up per-hour totals into data/hourly.jsonl (survives restarts, rebuilds itself if you yank the power).
• Calculates — rolling 24-hour window: exact bytes written in the last 24h, GB/h, GB/day, implied total TBW from percentage_used, remaining TB, and a projected life-remaining breakdown. Warming-up badge until it has 24h of coverage — no fake confidence.
• Shows off — dense, live dashboard with wear-over-time + trailing-24h per-hour bars, sticky header, live countdown, and stale warnings if the daemon dozes off.

You need

• Python 3.7+
• smartmontools (smartctl)
• Root-ish access to read NVMe SMART (passwordless smartctl or just run with sudo — your call)

The sudo dance (one time)

Fenris runs sudo -n smartctl ... so it doesn't get stuck asking for a password mid-nap:

sudo visudo
# add this line (swap in your username):
youruser ALL=(root) NOPASSWD: /usr/sbin/smartctl

No sudo? Run the whole thing with sudo and it'll still behave.

Get it running — 30 seconds

The cozy way

./fenris.sh
# pick 1) Start monitoring → choose device / interval / port → done

The no-nonsense way

python3 fenris.py start                          # defaults: /dev/nvme0, every 300s, port 8420
python3 fenris.py start --interval 60 --port 9000  # if you're impatient
python3 fenris.py status                         # "are we live? how's the drive?"
python3 fenris.py sample                         # one sneaky sample right now
python3 fenris.py stop                           # tuck it back in

Dashboard lives at http://localhost:8420 (or whatever port you chose).

The menu, demystified

Run ./fenris.sh and you'll get:

 1) Start monitoring (background daemon + dashboard)
 2) Stop monitoring
 3) Status / current wear stats
 4) Take one sample right now
 5) Open dashboard URL
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 h) Help / how this works
 q) Exit (go touch grass)

What Fenris jots down

Field	What's the gossip?
percentage_used	The drive's own wear-o-meter (0–100%)
bytes_written / bytes_read	Lifetime totals — the receipts
available_spare	Spare blocks left (%)
media_errors	Uncorrectable boo-boos
power_on_hours	How long it's been awake
temperature_c	Is it sweating?
critical_warning	NVMe's panic flags

Hourly rollups also stash bytes_written per hour, pct_start/pct_end, and temp peaks — so the 24h math stays honest.

The dashboard — what's on screen

• Hero card: Projected life remaining — big, friendly 361 d 2 h (plus ≈ 361 days · ≈ 8666 hours · ≈ 0.99 years), backed by ~280 GB/day and ~101 TB left of ~202 TB total on the test box.
• Data written (24h) — exact GB in the rolling window + coverage (10.4h of 24h until warmed up).
• Write rate — GB/h and GB/day, live.
• Wear, spare, temp, errors, power-on — the usual suspects, with progress bars and polite color-coding.
• Two charts, side by side: wear over time + trailing-24h hourly write bars (with a cheeky "now" bar for the current partial hour).
• Live plumbing: polling synced to your interval, ETag-cached, countdown to next sample, warming-up + stale banners, pauses when you hide the tab (saves your battery, you're welcome).

API for the tinkerers: GET /api/data · /api/hourly · /api/summary · /api/config · /api/status — all JSON, all friendly.

Where's my stuff?

fenris/
├── fenris.py                          # the whole show — daemon + server + math
├── fenris.sh                          # the cozy menu
├── README.md                          # hi — you're here
├── assets/bongbetic-brand/            # Bongbetic wordmarks & glyphs (for Gitea + dashboard)
└── data/
    ├── history.jsonl                  # raw samples (JSONL, append-only)
    ├── hourly.jsonl                   # per-hour rollups (auto-rebuilt on restart)
    ├── fenris.pid                     # daemon PID
    └── fenris.log                     # daemon chatter

CLI cheat sheet

python3 fenris.py start  [--device /dev/nvme0] [--interval 300] [--port 8420]
python3 fenris.py stop
python3 fenris.py status
python3 fenris.py sample [--device /dev/nvme0]
python3 fenris.py run    # foreground mode — what `start` spawns internally

Oops — troubleshooting without the tears

"smartctl not found"

sudo apt install smartmontools    # Debian/Ubuntu
sudo pacman -S smartmontools      # Arch — you already knew

"needs root" / permission denied Set up the passwordless line above, or just sudo ./fenris.sh.

Dashboard says "stale" Daemon napped or crashed. python3 fenris.py status will tell you. Kick it again with start.

Only 10 hours of data and it says "preliminary"? That's honesty, not a bug. It needs 24h of real writes to give a tight estimate. Let it simmer — the number gets sharper every hour.

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_{Fenris 🐺 — by Bongbetic · Be kind to your SSD and it'll be kind to you.}