feat: relocate D3 SSD from tsys4 USB to tsys5 SAS on Friday

Deep-dive on tsys4/5 storage controllers revealed:
- tsys4: 4-port SATA, all occupied; D3 SSD is USB 2.0
- tsys5: LSI SAS1068E (8-port, 5 free) + ICH10 SATA (2 free) + USB 3.0

Decision: move D3 (SK hynix SSD) to a tsys5 SAS port. Eliminates USB
bottleneck and consolidates all fast storage on tsys5: NVMe (local) +
D3 SSD + T5-SSD + 4 HDD exports.

Updated storage architecture, speed tiers, critical VM placement,
failure survival matrix, StorageClass design, and Friday plan.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

K8S.md

@@ -326,13 +326,18 @@ spec:
       storage: 50Gi
 ```
 
-### 6.3 NFS-SSD tier (D3 and T5-SSD)
+### 6.3 NFS-SSD tier (D3 and T5-SSD -- both on tsys5 after Friday)
 
-The SSD NFS exports are a middle tier. Use cases:
-- **D3 (tsys4, 445 GB free):** CI/CD artifacts, container image cache for
-  sectestbed nodes. Currently 99% empty.
-- **T5-SSD (tsys5, 140 GB free):** SIEM databases, monitoring data. Currently
-  35% used by ultix-streaming.
+The SSD NFS exports are a middle tier. **Both consolidated on tsys5** after
+the Friday D3 relocation:
+- **D3 (tsys5 SAS, 445 GB free):** CI/CD artifacts, container image cache,
+  UCS/LDAP. Currently 99% empty. Fastest NFS tier after the move off USB.
+- **T5-SSD (tsys5 SAS, 140 GB free):** SIEM databases, monitoring data.
+  Currently 35% used by ultix-streaming.
+
+**tsys5 is the fast-tier hub:** NVMe (local) + D3 SSD + T5-SSD all on one host.
+This simplifies the StorageClass design -- latency-sensitive PVCs target
+tsys5 exports, bulk PVCs target either server.
 
 ### 6.4 NFS data distribution across storage servers