# Stage 1B round 2: USB05 and USB01 exchanged

Status: complete
Type: evidence
Updated: 2026-08-01
Next Action: none; retain as historical round evidence for the completed broad baseline

Project Map: work/maps/map-smi-firmware-stabilization-and-qualification.md
Workpackage: work/wp/completed/wp-restore-broad-usb-compatibility-baseline.md
Checklist: work/checklists/checklist-stage-1b-four-drive-usb-compatibility-baseline.md

## Allocation and fresh session

| Controller | USB drive | Media generation | Handoff acceptance |
| --- | --- | ---: | ---: |
| A / `1751136` | `USB05_4G` | `2` | `15` |
| B / `1751219` | `USB01_2G` | `2` | `15` |

Both exchanged drives mounted on their first insertion with zero handoff and
system status. Each exposed both WAV files and the round 1 recovery image.
No retry, VBUS diagnostic, power cycle, remount, optional SCSI command, or
drive-specific logic was used.

## Controller workflow result

| Gate | USB05 on A | USB01 on B |
| --- | ---: | ---: |
| WAV load terminal | `1000`, PASS | `1000`, PASS |
| Sound 1 final state | idle, errors `0` | idle, errors `0` |
| PID request | accepted, errors `0` | accepted, errors `0` |
| Image result / progress | success / `1000` | success / `1000` |
| Image bytes / writes / maximum | `8,388,864 / 8,193 / 1,024` | `8,388,864 / 8,193 / 1,024` |
| Image elapsed | `239.68 s` | `415.09 s` |
| Image FileX error count / first / last | `0 / 0 / 0` | `0 / 0 / 0` |
| HPT request / records | `2 / 65` healthy | `2 / 61` degraded |
| HPT gaps / complete / published | `0 / 1 / 1` | `0 / 1 / 1` |
| HPT/USB/first USB failure | `0 / 0 / 0` | `0 / 0 / 0` |
| HPT bytes / writes / maximum | `3,990 / 4 / 1,024` | `3,739 / 4 / 1,024` |
| Final HPT/SSP/system errors | `0 / 0 / 0` | `0 / 0 / 0` |

This second publication exercised the normal prior-image backup, replacement,
and cleanup path. Unlike first publication, no accepted prior-image
`FX_NOT_FOUND` probe was recorded; all FileX telemetry remained zero.

The image timing follows the drive across controllers: `USB05_4G` measured
`239.87 s` on B and `239.68 s` on A, while `USB01_2G` measured `407.72 s` on A
and `415.09 s` on B. The common 1 KiB path is compatible on both controllers,
but its transaction overhead exposes a repeatable drive-dependent speed gap.

## Independent Pi validation

Read-only FAT checks reached the last sector, found two consistent FATs, no
lost or cross-linked clusters, and left both filesystems unchanged. The known
Windows root-label versus blank boot-label notice remained unchanged.

- Both drives retain the exact `8,388,864`-byte recovery image with SHA-256
  `908966E3460C1594D21DE0B379BE2B06F1D51057A7EC5D1C25D0540F2381D7D9`.
- Both contain two distinct 225-byte PID files; all four PID files hash to
  `6BCB89F2EFACC503B950EF00151A51AF8353C40B53781110C14DDC441737FC3A`.
- `USB05_4G` contains `R1B_USB05.csv` with a 61-record `COMPLETE` trailer and
  `R2A_USB05.csv` with a 65-record `COMPLETE` trailer.
- `USB01_2G` contains `R1A_USB01.csv` with a 65-record `COMPLETE` trailer and
  `R2B_USB01.csv` with a 61-record `COMPLETE` trailer.
- Both WAV hashes remain unchanged from pretest/round 1.
- No `.tmp`, `.part`, or `.bak` file is present.
- No USB reset, SCSI sense, medium, buffer-I/O, offline, or block I/O error was
  logged. Both drives were left on the Pi and unmounted.

## Raw evidence

- `work/evidence/hpt-log-store-circular-mirror/controller-a/stage1b-round2-usb05-20260731/`
- `work/evidence/hpt-log-store-circular-mirror/controller-b/stage1b-round2-usb01-20260731/`

## Disposition

Round 2 passes. `USB01_2G` and `USB05_4G` have now passed the complete common
workflow on both hardware variants, supplying four of eight required
controller/drive observations. Stage 1B and Stage 2 remain gated by rounds 3
and 4 plus USB09 regression.
