# Failure-prone SD-card reference identification

Captured: 2026-07-14
Source: Notion page `553 issues`
Source URL: https://app.notion.com/p/39c10e2686d880c5a64efe3c7fe7cd62
User disposition: original SD card that becomes corrupted with the old
firmware/code, historically after approximately one or two days of logging

## Preserved image

- Evidence file:
  `work/evidence/notion-sd-card/failure-reference-sandisk-edge-8gb.heic`
- Original Notion attachment:
  `work/evidence/notion-sd-card/notion-553-02.heic`
- Size: 535,714 bytes
- SHA-256:
  `06D921FCCDC9ED3D3000F3AACD412DDF82AB3487355F1523A52ECE64F9195B91`

The descriptive evidence file is byte-for-byte identical to the preserved
Notion attachment.

## Identification from visible label

| Attribute | Identification | Confidence |
| --- | --- | --- |
| Brand | SanDisk | high |
| Product family | EDGE | high |
| Capacity | 8 GB | high |
| Form factor | microSD | high |
| Capacity standard | microSDHC | high; visible microSDHC mark |
| Bus marking | UHS-I | high; Roman numeral I visible |
| SD speed class | Class 4 | high; circled 4 visible |
| UHS speed class | no U1/U3 mark visible | high for this face only |
| Country marking | Made in China | high |
| Faint printed code | appears similar to `XC100TERM05S`; not confirmed | low |
| Exact SanDisk MPN/SKU | not established by this image | unknown |
| CID, serial, manufacturing lot/date | not captured | unknown |
| Filesystem/allocation-unit format | not captured by the photo | unknown |

## Qualification role

Treat this physical card as the **known failure-prone reference/control card**.
The accelerated endurance routine should reproduce its historical corruption
quickly enough to discriminate between firmware/card combinations. Preserve
the card in its failing state before formatting when possible, including a
sector image, host filesystem-repair report, directory/file listing, FileX
status, controller counters, and hashes of every readable log file.

Run the same controlled test on this card and the known-working SanDisk
Industrial 8 GB reference. A useful firmware improvement must do both:

1. make this EDGE card complete accelerated logging, readback, restart, and
   host filesystem checks without corrupt blocks, sectors, directories, or
   files; and
2. retain reliable behavior on the Industrial reference card without reducing
   normal control, UI, alarm, communication, chart, or export operation.

## Reference comparison

| Role | Visible product | Capacity | Visible speed markings | Historical disposition |
| --- | --- | ---: | --- | --- |
| failure-prone control | SanDisk EDGE | 8 GB | UHS-I, Class 4 | corrupts with old code after roughly 1–2 days |
| known-working control | SanDisk Industrial | 8 GB | UHS-I, U1, Class 10 | works with old code |

The label differences are useful test variables, but they do not prove that
speed class caused the corruption. Firmware write ordering, flush behavior,
power interruption, card controller/flash generation, filesystem geometry,
wear, and sample-to-sample variation must also be measured.

## Evidence limitation

Obtain a reverse-side photo, packaging/receipt traceability, and electronic CID
before translating this reference into an exact purchasing specification. Do
not generalize one failing physical sample to every SanDisk EDGE card without
multi-sample evidence.

