# Unraid Drive Replacement Plan

## Risk Tolerance: 20% cumulative failure probability

## Current Array (as of 2026-03-28)

| Slot | Model | Serial | Age | Est. AFR | Notes |
|------|-------|--------|-----|----------|-------|
| Parity 1 | ST8000DM004 8TB SMR | ZCT2K65B | 5.3 yr | ~4.5% | Had 180 GP errors (cleared) |
| Parity 2 | ST8000DM004 8TB SMR | ZCT2K5PQ | 5.3 yr | ~3.5% | Had 19 GP errors (cleared) |
| Disk 1 | ST8000DM004 8TB SMR | ZCT2K3FF | 5.3 yr | ~2.75% | Same batch as parity drives |
| Disk 2 | ST8000DM004 8TB SMR | ZCT2K51K | 5.3 yr | ~2.75% | 1 CRC error |
| Disk 3 | ST8000DM004 8TB SMR | ZCT3XAEJ | 4.8 yr | ~3.5% | Had 10 GP errors, 2 CRC, 72K load cycles |
| Disk 4 | WD40EFRX 4TB CMR | WD-WCC7K2YF4TDJ | 6.6 yr | ~2.5% | Pristine SMART, lowest priority |
| Disk 5 | ST8000DM004 8TB SMR | ZR14W632 | 2.5 yr | ~1.75% | 56C lifetime max |
| Disk 6 | ST8000DM004 8TB SMR | ZR150CVS | 2.5 yr | ~1.75% | Clean |
| Cache | Samsung 970 EVO 1TB | — | — | — | 1% wear, excellent |

All 7 Seagate drives are consumer desktop SMR (not NAS-grade). Dual parity protects against up to 2 simultaneous failures.

## Timeline

### March 2027 — Parity 1

| | Details |
|--|---------|
| Remove | ST8000DM004 8TB (ZCT2K65B) |
| Install | **Seagate Exos X24 24TB** (ST24000NM002H) |
| Cost | ~$380 |
| Time | Parity sync ~18 hrs |
| Risk at swap | ~20% |

**Steps:** Stop array > power down > swap drive > power up > assign to Parity 1 slot > start array > parity sync

Keep old drive labeled as cold spare.

---

### May 2028 — Parity 2 + Disk 3

Do these a week apart. Parity first, then data drive.

**Parity 2:**

| | Details |
|--|---------|
| Remove | ST8000DM004 8TB (ZCT2K5PQ) |
| Install | **Seagate Exos X24 24TB** (ST24000NM002H) |
| Cost | ~$380 |
| Time | Parity sync ~18 hrs |

**Disk 3 (one week later):**

| | Details |
|--|---------|
| Remove | ST8000DM004 8TB (ZCT3XAEJ) |
| Install | **Toshiba MG10 20TB** (MG10ACA20TE) |
| Cost | ~$300 |
| Time | Rebuild ~18-20 hrs |

Combined cost: ~$700. Risk at swap: ~20%. After this, monthly failure rate drops to ~0.9%.

---

### Mid 2030 — Disks 1 & 2

| Slot | Install | Cost |
|------|---------|------|
| Disk 1 | **Toshiba MG10 20TB** | ~$300 |
| Disk 2 | **WD Ultrastar HC560 20TB** | ~$300 |

Same batch as old parity drives, will be ~9 years old. Combined: ~$600.

---

### Whenever — Disks 4, 5, 6

Low risk, replace opportunistically on sales. ~$300 each, ~$900 total.

## Total Cost

| Phase | When | Cost | Running Total |
|-------|------|------|--------------|
| Parity 1 | Mar 2027 | $380 | $380 |
| Parity 2 + Disk 3 | May 2028 | $700 | $1,080 |
| Disks 1 & 2 | Mid 2030 | $600 | $1,680 |
| Disks 4, 5, 6 | Whenever | $900 | $2,580 |

## If a Drive Fails Before Its Scheduled Replacement

- **Parity drive fails:** Buy 1x Exos X24 24TB, swap, parity sync
- **Data drive fails:** Need 2 drives — 1x Exos X24 24TB (new parity, since 20TB data > 8TB parity) + 1x 20TB data drive. Upgrade parity first, then replace data drive.

Array stays online with a failed drive (dual parity). No data loss. Performance reduced until rebuild.

## Final Array

| Slot | Drive | Brand | Size |
|------|-------|-------|------|
| Parity 1 | Exos X24 | Seagate | 24TB |
| Parity 2 | Exos X24 | Seagate | 24TB |
| Disk 1 | MG10 | Toshiba | 20TB |
| Disk 2 | HC560 | WD | 20TB |
| Disk 3 | MG10 | Toshiba | 20TB |
| Disk 4 | TBD | TBD | 20TB+ |
| Disk 5 | HC560 | WD | 20TB |
| Disk 6 | MG10 | Toshiba | 20TB |

Usable capacity: ~120TB (up from ~48TB). All CMR, all enterprise/NAS-grade, 3 brands, 5-year warranties.

## Pending Config Fixes

- [ ] Remove compose.manager plugin (deprecated, still installed)
- [ ] Set share security to Private (disk shares still "public")
- [ ] Move domains share to cache (useCache should be "prefer")
- [ ] Set up email/push notifications for drive alerts
- [ ] Configure UPS auto-shutdown (CyberPower CP1500, nut-dw plugin installed)
- [ ] Enable XMP in BIOS (RAM running 1333 MT/s, rated for 1600 MT/s)
- [ ] Verify appdata backups — test a restore