diff --git a/notes/Unraid Drive Replacement Plan.md b/notes/Unraid Drive Replacement Plan.md
index 72e2472..37a9646 100644
--- a/notes/Unraid Drive Replacement Plan.md	
+++ b/notes/Unraid Drive Replacement Plan.md	
@@ -25,6 +25,25 @@
 
 Total data stored: ~25TB, growing ~1TB/year
 
+## Drive Buyer's Guide
+
+Only 3 manufacturers make 3.5" HDDs: Seagate, WD, and Toshiba. All others (Samsung, Hitachi, HGST, Maxtor) were acquired.
+
+| Brand | Line | Tier | CMR | RPM | Workload | MTBF | Warranty | ~16TB Price |
+|---|---|---|---|---|---|---|---|---|
+| **Seagate** | BarraCuda | Consumer | **SMR** | 5400 | — | — | 2 yr | ~$250 |
+| | IronWolf | Home NAS | CMR | 7200 | 180 TB/yr | 1M hrs | 3 yr | ~$210 |
+| | IronWolf Pro | Pro NAS | CMR | 7200 | 300 TB/yr | 1.2M hrs | 5 yr | ~$230 |
+| | Exos (X18/X20/X24) | Enterprise | CMR | 7200 | 550 TB/yr | 2.5M hrs | 5 yr | ~$220 |
+| **WD** | Red | Light NAS | **SMR** | 5400 | 180 TB/yr | 1M hrs | 3 yr | ~$210 |
+| | Red Plus | Home NAS | CMR | 5400-7200 | 180 TB/yr | 1M hrs | 3 yr | ~$210 |
+| | Red Pro | Pro NAS | CMR | 7200 | 300 TB/yr | 1M hrs | 5 yr | ~$230 |
+| | Ultrastar | Enterprise | CMR | 7200 | 550 TB/yr | 2.5M hrs | 5 yr | ~$220 |
+| **Toshiba** | N300 | Home NAS | CMR | 7200 | 180 TB/yr | 1M hrs | 3 yr | ~$200 |
+| | MG Series | Enterprise | CMR | 7200 | 550 TB/yr | 2.5M hrs | 5 yr | ~$210 |
+
+**Avoid SMR drives** (BarraCuda, WD Red no suffix) — terrible for Unraid parity rebuilds. Home NAS tier (CMR) is perfectly adequate; enterprise is worth it when the price gap is small (<$15/drive). Best deals typically appear during Black Friday / Cyber Monday (20-40% off).
+
 ## Shopping List
 
 | Drive | Model | Purpose | Est. Price |