Add .gitignore for the Zenodo API token (secret, kept out of git)

One page, two clear sections each led by its chart: price-per-TB over time
(the crunch), then how often drives go on sale. Adds sale-frequency-trend.png
(branded chart matching the $/TB one).

.gitignore

@@ -0,0 +1,2 @@
+# Secrets - never commit (canonical copy lives in sysarch, not here)
+.zenodo-token

README.md

@@ -14,6 +14,8 @@ Maintained at [nasdisks.com](https://www.nasdisks.com/), where the same data pow
 
 ## What's inside
 
+**Price trends:** [`price-trends/`](price-trends/) - two charts of the NAS drive market over time: the monthly median \$/TB (consumer vs enterprise, the storage price crunch), and how often each drive goes on sale and how deep. Computed data plus the charts.
+
 | File | Rows | What it is |
 |------|------|------------|
 | [`data/drives-2026-09-04.csv`](data/drives-2026-09-04.csv) | 273 | The headline file: one flat row per drive, all specs and failure rate combined. |

price-trends/README.md

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+# NAS drive price trends
+
+Two computed views of the NAS hard-drive market over time, both from our daily price history and maintained at [nasdisks.com](https://www.nasdisks.com/): what a terabyte costs, and how often drives actually go on sale. Scope throughout: in-production 8TB+ NAS hard drives, US, new in-stock prices, compiled from Amazon price history.
+
+## Price per terabyte over time
+
+Monthly median price-per-terabyte, split into the two tiers people choose between: consumer NAS (WD Red / IronWolf class) and enterprise (Exos / MG / Ultrastar).
+
+![Median dollars per TB, consumer NAS vs enterprise](nas-price-trend.png)
+
+Median price-per-TB sat flat around \$20/TB through 2024 and most of 2025, then roughly doubled to the mid-\$40s/TB from late 2025, and has held there since. Both tiers moved together: among new drives, enterprise is not the price-per-TB bargain it's assumed to be, and both got hit about equally. The usual driver is the AI datacenter buildout pulling high-capacity nearline supply. Because the tiers track each other, there's no reliable price-per-TB win from picking enterprise over consumer among new drives; the one genuine discount is the recertified/refurbished enterprise market, which isn't included here.
+
+**Method.** For each month, take each drive's average price-per-TB across its logged days, then the median of those per-drive values across drives (so a model with more logged days doesn't skew the month). 8TB and up because small drives carry a much higher price-per-TB, and which small SKUs happen to be in stock would swing an all-capacity median for reasons unrelated to prices actually moving.
+
+**File:**
+
+- [`monthly-median-per-tb.csv`](monthly-median-per-tb.csv) - `month`, `consumer_usd_per_tb`, `enterprise_usd_per_tb`.
+
+**Interactive version** (hover, zoom, and a capacity-matched cheapest-per-TB table): [nasdisks.com/articles/nas-drive-price-crunch](https://www.nasdisks.com/articles/nas-drive-price-crunch/).
+
+## How often drives go on sale
+
+How often each current drive actually dips *on sale*, and how deep.
+
+![Share of days on sale, consumer NAS vs enterprise](sale-frequency-trend.png)
+
+NAS drives (WD Red / IronWolf class, including the Pro lines) go on sale several times more often than enterprise/datacenter drives - roughly one day in ten vs one in forty - though the cut is about the same size when it happens (~10% typical, ~30% at the deepest). Seagate IronWolf Pro goes on sale most often; Exos and Ultrastar barely move. It's a difference in frequency, not depth.
+
+**Method.** For each day we compare a drive's best price to a centred rolling median of its own recent price, so a genuine dip counts but the long price climb is not mistaken for a discount, then count the days sitting 5%+ below that baseline. A "sale event" is a run of such days.
+
+**Files:**
+
+- [`sale-frequency-by-model.csv`](sale-frequency-by-model.csv) - per drive: `brand`, `line`, `capacity_tb`, `segment` (`consumer` = NAS lines incl. Pro, `enterprise` = datacenter), `pct_days_on_sale`, `typical_discount_pct`, `deepest_discount_pct`, `sale_events`, `days_observed`.
+- [`sale-frequency-weekly.csv`](sale-frequency-weekly.csv) - weekly share of tracked days on sale per tier: `week_start`, `consumer_pct_days_on_sale`, `enterprise_pct_days_on_sale`.
+
+**Interactive version** (weekly chart + sortable per-model table): [nasdisks.com/articles/nas-drive-sale-frequency](https://www.nasdisks.com/articles/nas-drive-sale-frequency/).
+
+## Using this data
+
+The figures here (monthly medians and sale-frequency aggregates) are free to use, with a credit to `nasdisks.com` (a link back is appreciated). They are computed aggregate statistics, provided as-is, and separate from the repository's CC BY 4.0 license, which covers the drive specs and CMR/SMR data.

price-trends/monthly-median-per-tb.csv

@@ -0,0 +1,28 @@
+month,consumer_usd_per_tb,enterprise_usd_per_tb
+2024-07,19.94,20.93
+2024-08,20.03,22.38
+2024-09,20.38,21.43
+2024-10,20.52,21.84
+2024-11,20.07,21.11
+2024-12,20.74,20.81
+2025-01,21.00,21.22
+2025-02,21.17,21.58
+2025-03,21.00,21.75
+2025-04,20.82,23.24
+2025-05,21.30,21.45
+2025-06,20.42,21.87
+2025-07,20.87,21.48
+2025-08,21.01,20.51
+2025-09,21.50,20.47
+2025-10,22.34,21.17
+2025-11,20.78,22.25
+2025-12,23.67,23.07
+2026-01,27.95,25.02
+2026-02,26.05,27.94
+2026-03,33.43,31.48
+2026-04,39.05,37.99
+2026-05,39.12,39.31
+2026-06,43.52,41.69
+2026-07,44.95,45.31
+2026-08,44.01,42.54
+2026-09,44.37,43.45

price-trends/sale-frequency-by-model.csv

@@ -0,0 +1,66 @@
+brand,line,capacity_tb,segment,pct_days_on_sale,typical_discount_pct,deepest_discount_pct,sale_events,days_observed
+Seagate,"IronWolf Pro",20,consumer,25.4,9.5,21.4,31,710
+Seagate,"IronWolf Pro",12,consumer,19.6,8,26.4,26,679
+Seagate,"IronWolf Pro",16,consumer,18.9,9.1,24.2,24,694
+WD,"Red Plus",10,consumer,15.2,10.7,30.5,37,796
+Seagate,"IronWolf Pro",24,consumer,15,8.3,16.7,21,713
+WD,"Red Pro",24,consumer,14.9,16.5,35.3,18,403
+Seagate,"IronWolf Pro",14,consumer,13.7,13.8,34.8,28,782
+WD,Gold,24,enterprise,11,7.6,24,11,544
+WD,"Red Plus",12,consumer,10.2,9.4,46.6,27,775
+WD,"Red Pro",18,consumer,10,8.7,31,29,763
+WD,"Red Plus",8,consumer,9.5,9,27,22,781
+WD,"Red Pro",8,consumer,9.5,11.1,28.9,15,791
+WD,"Red Pro",22,consumer,9.5,8.5,29.7,17,767
+WD,Gold,12,enterprise,9.4,7.7,21.3,14,758
+Seagate,IronWolf,10,consumer,8.8,17.4,31.4,26,794
+WD,"Red Pro",14,consumer,8.7,8.1,26.4,20,789
+WD,Gold,24,enterprise,8.7,8.2,29.3,16,680
+WD,Gold,18,enterprise,8.5,7.8,26.6,21,785
+Seagate,"IronWolf Pro",10,consumer,8.2,12.9,42.2,18,794
+Toshiba,N300,8,consumer,8.1,19.3,36.3,8,442
+WD,"Red Pro",20,consumer,7.6,10.4,27.6,12,728
+Seagate,"Exos X20",20,enterprise,7.4,9.7,44.6,11,551
+WD,Gold,22,enterprise,7.1,7.9,34.3,16,760
+WD,"Red Pro",12,consumer,6.9,16.3,35.4,17,611
+WD,Gold,20,enterprise,6.1,6.4,26.4,12,625
+WD,"Ultrastar DC HC320",8,enterprise,6,10,47.1,16,745
+Seagate,"Exos X22",22,enterprise,5.9,8.8,39.2,4,323
+Toshiba,MG09,18,enterprise,5.5,8.2,30.1,12,793
+WD,"Red Pro",16,consumer,5.4,9.1,33.5,18,793
+Toshiba,N300,10,consumer,5.4,7.2,50.2,5,331
+Seagate,"Exos 7E8",8,enterprise,5,10.5,28.7,13,793
+Toshiba,MG07,14,enterprise,5,12.1,64.8,11,780
+WD,"Ultrastar DC HC590",26,enterprise,4.6,5.6,34.9,2,324
+WD,Gold,10,enterprise,4.2,10.4,57.4,6,792
+WD,Gold,14,enterprise,4.2,16,43,12,766
+WD,"Ultrastar DC HC550",18,enterprise,4.2,10.7,15.2,7,730
+Toshiba,MG06,10,enterprise,3.6,29.9,42.4,10,731
+Toshiba,MG07,12,enterprise,3.5,11.3,35.6,7,771
+Toshiba,N300,16,consumer,3.3,28.2,29,3,481
+Toshiba,MG09,16,enterprise,3.3,18.7,20,3,608
+WD,"Red Pro",10,consumer,3,25.2,53.5,5,725
+WD,"Ultrastar DC HC520",12,enterprise,3,9.9,33.1,5,600
+WD,"Ultrastar DC HC560",20,enterprise,2.7,5,18.5,4,711
+WD,Gold,16,enterprise,2.6,23.3,58.9,8,681
+Toshiba,N300,12,consumer,2.5,8.4,19.8,3,395
+Toshiba,MG10,20,enterprise,2.4,15.1,40.8,5,736
+Seagate,"Exos X18",18,enterprise,2.3,9,29.3,5,660
+Seagate,"Exos 7E10",10,enterprise,2.2,6.3,21.5,5,730
+WD,Gold,8,enterprise,1.9,8.8,8.8,1,724
+WD,"Ultrastar DC HC550",16,enterprise,1.9,10,11.5,5,730
+Toshiba,MG10,22,enterprise,1.8,12.6,20.4,4,792
+Toshiba,MG09,18,enterprise,1.8,7.3,46.7,3,763
+WD,"Ultrastar DC HC330",10,enterprise,1.4,5.7,10.3,4,793
+WD,"Ultrastar DC HC530",14,enterprise,1.2,13.1,30.5,3,730
+Seagate,"Exos X18",16,enterprise,1.1,48.3,48.4,1,437
+Toshiba,MG06,8,enterprise,0.8,68.6,68.6,3,633
+Seagate,"Exos X18",18,enterprise,0.6,21.6,63.1,2,793
+Toshiba,MG11,24,enterprise,0.6,5.3,5.3,2,494
+Seagate,"Exos X16",16,enterprise,0.5,6.3,7.1,2,556
+Toshiba,MG07,14,enterprise,0.4,6.2,6.2,1,793
+WD,"Ultrastar DC HC580",24,enterprise,0.3,72.7,72.7,1,360
+Seagate,"Exos X24",24,enterprise,0.1,5.9,5.9,1,709
+WD,"Ultrastar DC HC570",22,enterprise,0,0,0,0,730
+Seagate,"Exos 7E10",8,enterprise,0,0,0,0,197
+Toshiba,MG08,16,enterprise,0,0,0,0,222

price-trends/sale-frequency-weekly.csv

@@ -0,0 +1,117 @@
+week_start,consumer_pct_days_on_sale,enterprise_pct_days_on_sale
+2024-07-01,0,0
+2024-07-08,10.9,0
+2024-07-15,13.4,1.9
+2024-07-22,7.6,1.4
+2024-07-29,10.1,1
+2024-08-05,0.8,0
+2024-08-12,10.1,0
+2024-08-19,15.1,3.6
+2024-08-26,0,4
+2024-09-02,8,1.7
+2024-09-09,22,6.5
+2024-09-16,10.1,9
+2024-09-23,2.5,2.5
+2024-09-30,8.2,2.1
+2024-10-07,10.3,3.4
+2024-10-14,11.9,7.1
+2024-10-21,19.8,4.5
+2024-10-28,15.1,1.8
+2024-11-04,13.5,0.9
+2024-11-11,4.1,0
+2024-11-18,21.8,3.1
+2024-11-25,25.6,4.3
+2024-12-02,10.5,0.8
+2024-12-09,10,5.9
+2024-12-16,4.8,4.2
+2024-12-23,0.8,0.4
+2024-12-30,2.4,2.2
+2025-01-06,13.1,1.8
+2025-01-13,7.4,1.7
+2025-01-20,10.3,2.9
+2025-01-27,19,3.3
+2025-02-03,4,0
+2025-02-10,7.1,0
+2025-02-17,14.3,1.6
+2025-02-24,9.2,2.4
+2025-03-03,8.7,6.1
+2025-03-10,0,2.3
+2025-03-17,2.2,0
+2025-03-24,5.9,1.2
+2025-03-31,21.7,4.2
+2025-04-07,13.1,2.7
+2025-04-14,8.8,1.5
+2025-04-21,8.1,1.1
+2025-04-28,7.1,1.9
+2025-05-05,5.2,1.1
+2025-05-12,9.1,0
+2025-05-19,8.4,3
+2025-05-26,3.9,4.5
+2025-06-02,11.7,4.1
+2025-06-09,3.9,2.2
+2025-06-16,5.3,1.1
+2025-06-23,3.9,4.8
+2025-06-30,14.3,5.5
+2025-07-07,24.5,2.9
+2025-07-14,8.3,1.1
+2025-07-21,10.6,2.6
+2025-07-28,21.4,3.8
+2025-08-04,6.8,3.8
+2025-08-11,3.8,1.9
+2025-08-18,9.7,2.6
+2025-08-25,11.8,1.1
+2025-09-01,5.6,1.5
+2025-09-08,8.2,0.7
+2025-09-15,7.4,0
+2025-09-22,5.2,1.1
+2025-09-29,5.6,2.3
+2025-10-06,11.4,4.2
+2025-10-13,8.2,4.8
+2025-10-20,13.8,4
+2025-10-27,18.8,2.9
+2025-11-03,14.9,2.9
+2025-11-10,6.3,2.5
+2025-11-17,17.5,4.3
+2025-11-24,22.8,1.1
+2025-12-01,12.4,6.1
+2025-12-08,12.8,9.6
+2025-12-15,17.3,3.3
+2025-12-22,18.5,1.8
+2025-12-29,7.5,0.7
+2026-01-05,5.8,3.7
+2026-01-12,20.8,4.8
+2026-01-19,8.5,3
+2026-01-26,12.6,5.5
+2026-02-02,12.5,6
+2026-02-09,7.4,3.3
+2026-02-16,3.5,4.8
+2026-02-23,4.5,11.4
+2026-03-02,10.1,4.6
+2026-03-09,7.2,0.9
+2026-03-16,6.7,2.1
+2026-03-23,13.1,5.2
+2026-03-30,20,7
+2026-04-06,9,5.9
+2026-04-13,25,8.6
+2026-04-20,19.3,2.9
+2026-04-27,7.5,0.8
+2026-05-04,9.8,2.8
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+2026-05-18,13.6,8.7
+2026-05-25,8.4,4.7
+2026-06-01,15.1,10.5
+2026-06-08,22.4,12.4
+2026-06-15,21.8,12.5
+2026-06-22,7.5,8.1
+2026-06-29,8.3,9.8
+2026-07-06,5.1,8.8
+2026-07-13,15.3,3.7
+2026-07-20,17.5,3.5
+2026-07-27,5.7,0
+2026-08-03,8.9,3.7
+2026-08-10,9.4,2
+2026-08-17,7.9,0.8
+2026-08-24,3.9,2.8
+2026-08-31,8.4,2.8
+2026-09-07,12.1,0.8
+2026-09-14,0,0