Scope licensing: CC BY 4.0 for our specs/CMR-SMR; Backblaze AFR under Backblaze terms

Backblaze Drive Stats forbids selling the data itself, which CC BY 4.0 permits,
so the failure-rate fields can't be CC BY 4.0. README now splits the licence and
a NOTICE documents the Backblaze-sourced fields (cite Backblaze; no resale of the
data; no endorsement). drives.json/csv re-exported from the corrected live API.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

NOTICE

@@ -0,0 +1,23 @@
+NOTICE - third-party data
+
+This repository combines two sources under two different sets of terms.
+
+1. Drive specifications and CMR/SMR classification
+   (c) nasdisks.com - https://www.nasdisks.com
+   Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0).
+   See LICENSE.
+
+2. Failure-rate data
+   Fields: afr_pct, reliability_drive_count, reliability_drive_days,
+   reliability_failures (in data/drives.csv and data/drives.json), and the
+   whole of data/backblaze-afr.csv.
+   Source: Backblaze Drive Stats
+   https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data
+
+   These figures are derived from Backblaze's published Drive Stats data and
+   remain subject to Backblaze's terms, NOT CC BY 4.0:
+     - cite Backblaze as the source;
+     - you may not sell the data itself (selling derivative works is allowed);
+     - you are solely responsible for how you use the data.
+
+   Backblaze does not endorse this project.

README.md

@@ -1,8 +1,8 @@
 # NAS drive dataset
 
-An open dataset of NAS hard drives: full specs, **CMR vs SMR**, and real-world **Backblaze annualized failure rates (AFR)**. 138 drives, 13 with a measured failure rate. Free for any use - including commercially - under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), provided you credit the source.
+An open dataset of NAS hard drives: full specs, **CMR vs SMR**, and real-world **Backblaze annualized failure rates (AFR)**. 138 drives, 13 with a measured failure rate. Our drive specs and CMR/SMR data are free to use - including commercially - under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) with credit; the Backblaze failure-rate fields stay under [Backblaze's own terms](#licence--attribution) (cite Backblaze; don't sell the data itself).
 
-Maintained at [nasdisks.com](https://www.nasdisks.com), where the same data drives a live price comparison across seven Amazon regions. This repo is the raw data on its own, with no strings beyond attribution.
+Maintained at [nasdisks.com](https://www.nasdisks.com), where the same data drives a live price comparison across seven Amazon regions.
 
 ## What's inside
 
@@ -53,16 +53,18 @@ curl -s https://www.nasdisks.com/data/drives.csv
 
 ## Licence & attribution
 
-Released under [Creative Commons Attribution 4.0 International (CC BY 4.0)](https://creativecommons.org/licenses/by/4.0/). Full legal code in [`LICENSE`](LICENSE).
+This dataset has two parts under two different sets of terms.
 
-You may copy, remix and redistribute the data, even commercially, as long as you credit the source. The required attribution:
+**Drive specs + CMR/SMR classification** - everything except the failure-rate fields - is our own work, released under [Creative Commons Attribution 4.0 International (CC BY 4.0)](https://creativecommons.org/licenses/by/4.0/) (full legal code in [`LICENSE`](LICENSE)). Copy, remix and redistribute it, even commercially, as long as you credit:
 
 ```
-NAS drive dataset by nasdisks.com, CC BY 4.0
+Drive specs & CMR/SMR by nasdisks.com, CC BY 4.0
 ```
 
 A link back to https://www.nasdisks.com satisfies it.
 
+**Failure-rate fields** - `afr_pct`, `reliability_drive_count`, `reliability_drive_days`, `reliability_failures` (in `drives.csv`/`drives.json`) and the whole of `backblaze-afr.csv` - come from [Backblaze Drive Stats](https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data) and stay under **Backblaze's terms, not CC BY 4.0**: cite Backblaze as the source, and you may not sell the data itself (selling derivative works is fine). Backblaze does not endorse this project. See [`NOTICE`](NOTICE).
+
 ## Updates
 
 The dataset is refreshed as the catalogue and Backblaze data change. The live endpoints above always reflect the current state; this repo is re-exported periodically.