obsidian-yanxin/notes/Unraid Drive Replacement Plan.md

Unraid Drive Replacement Plan

Goals

• Replace the 3 worst drives (both parity + Disk 3) with enterprise CMR
• Remove the smallest drive (Disk 4, 4TB) — too small to be useful
• Keep the 4 healthiest data drives running
• Reduce from 8 to 6 HDD drives
• Stay under 20% cumulative failure risk
• Total budget: ~$440

Current Array (as of 2026-03-28)

Slot	Model	Serial	Size	Age	Est. AFR	Health	Action
Parity 1	ST8000DM004 SMR	ZCT2K65B	8TB	5.3yr	~4.5%	Had 180 GP errors (cleared)	Replace
Parity 2	ST8000DM004 SMR	ZCT2K5PQ	8TB	5.3yr	~3.5%	Had 19 GP errors (cleared)	Replace
Disk 1	ST8000DM004 SMR	ZCT2K3FF	8TB	5.3yr	~2.75%	Clean, same batch as parity	Keep
Disk 2	ST8000DM004 SMR	ZCT2K51K	8TB	5.3yr	~2.75%	1 CRC error, otherwise clean	Keep
Disk 3	ST8000DM004 SMR	ZCT3XAEJ	8TB	4.8yr	~3.5%	Had 10 GP errors, 2 CRC, 72K load cycles	Remove
Disk 4	WD40EFRX CMR	WD-WCC7K2YF4TDJ	4TB	6.6yr	~2.5%	Pristine SMART, only 1.7TB used	Remove
Disk 5	ST8000DM004 SMR	ZR14W632	8TB	2.5yr	~1.75%	56C lifetime max, otherwise clean	Keep
Disk 6	ST8000DM004 SMR	ZR150CVS	8TB	2.5yr	~1.75%	Clean	Keep
Cache	Samsung 970 EVO	S5H9NS0N831296A	1TB	—	—	1% wear, excellent	Keep

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
Seagate Exos X18 16TB	ST16000NM000J	Parity 1	~$220
Seagate Exos X18 16TB	ST16000NM000J	Parity 2	~$220
		Total	~$440

Why 16TB parity for 8TB data drives: when a data drive eventually dies or fills up (~2030), you can drop in a 16TB replacement without touching parity. Buying 8TB parity now would mean buying parity drives again later — more expensive overall. The Exos X18 should last 8-12+ years in a home NAS, outlasting multiple generations of data drives.

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Phase 0 — Now (free)

Goal: Remove Disk 4 (WD Red 4TB) — too small to be useful

Disk 4 only has 1.7TB used. Other drives have 14.5TB of free space.

1. Open Unbalance plugin in Unraid WebGUI
2. Source: Disk 4
3. Destination: Disk 3, Disk 5, Disk 6 (most free space)
4. Start transfer (~30 min for 1.7TB)
5. Verify Disk 4 shows 0 bytes used
6. Stop array (Main → Array Operations → Stop)
7. Click on Disk 4 slot → set to No Device
8. Start array → check "Yes I want to do this" → confirm
9. Parity sync runs automatically (~12-18 hrs, array is usable during sync)
10. Once sync completes: power down, physically remove the 4TB drive, power up

Keep the WD Red 4TB as a cold backup drive — pristine SMART despite its age. Good for periodic offline backups via USB dock.

Result: 8 → 7 drives.

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Phase 1 — April 2027

Goal: Replace Parity 1, remove Disk 3

Cumulative failure risk reaches ~20% around this time. First purchase.

Buy: 1x Seagate Exos X18 16TB (~$220)

Step 1: Replace Parity 1

1. Stop array
2. Power down server
3. Locate Parity 1 drive (sdb, serial ZCT2K65B) and remove it
4. Install the new Exos X18 16TB in the same physical slot
5. Power up
6. Main page → verify new drive appears in the Parity 1 slot
7. Start array
8. Parity sync begins automatically (~12-18 hrs)
9. Array is fully usable during sync — avoid heavy writes for best performance
10. Wait for sync to complete (progress shown on Main page)

Step 2: Remove Disk 3

After parity sync completes:

11. Open Unbalance plugin
12. Source: Disk 3 (~4.3TB after absorbing some of Disk 4's data)
13. Destination: Disk 1, Disk 2, Disk 5, Disk 6
14. Start transfer (~2-4 hrs)
15. Verify Disk 3 shows 0 bytes used
16. Stop array
17. Click on Disk 3 slot → set to No Device
18. Start array → confirm → parity sync runs (~12-18 hrs)
19. Once sync completes: power down, physically remove Disk 3, power up

Disposal

• Old Parity 1 (ZCT2K65B): Recycle — worst error history in the array
• Old Disk 3 (ZCT3XAEJ): Recycle — GP errors + CRC errors + high load cycles

Result: 7 → 6 drives.

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Phase 2 — June 2027

Goal: Replace Parity 2

Buy: 1x Seagate Exos X18 16TB (~$220)

1. Stop array
2. Power down server
3. Locate Parity 2 drive (sdc, serial ZCT2K5PQ) and remove it
4. Install the new Exos X18 16TB in the same physical slot
5. Power up
6. Main page → verify new drive appears in the Parity 2 slot
7. Start array
8. Parity sync begins (~12-18 hrs)
9. Wait for completion

Disposal

• Old Parity 2 (ZCT2K5PQ): Recycle — 19 GP error history

Result: Still 6 drives. Migration complete.

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Final Array (June 2027)

Slot	Drive	Size	Used	Age	Health
Parity 1	Seagate Exos X18 (new)	16TB	—	New	Enterprise CMR, 5yr warranty
Parity 2	Seagate Exos X18 (new)	16TB	—	New	Enterprise CMR, 5yr warranty
Disk 1	ST8000DM004 (kept)	8TB	~6.6TB	6.3yr	Clean
Disk 2	ST8000DM004 (kept)	8TB	~6.5TB	6.3yr	1 CRC, otherwise clean
Disk 5	ST8000DM004 (kept)	8TB	~5.2TB	3.5yr	Clean
Disk 6	ST8000DM004 (kept)	8TB	~5.2TB	3.5yr	Clean

• Usable capacity: 29.2TB (4 × 7.3TB)
• Data stored: ~25TB, ~4TB free
• Growth runway: ~4 years at 1TB/yr before needing bigger data drives
• Annual failure rate: ~8% (down from ~19%)
• 2 empty drive bays for future expansion

Cost Summary

When	What	Cost
Now	Remove Disk 4	$0
Apr 2027	Exos X18 16TB (Parity 1)	$220
Jun 2027	Exos X18 16TB (Parity 2)	$220
Total		$440

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When a Data Drive Eventually Dies or Fills Up (~2030)

Since parity is already 16TB, just buy one replacement data drive up to 16TB. No parity upgrade needed.

Recommended replacements (for brand diversity):

• Toshiba MG08/MG10 16TB (~$200) — enterprise CMR
• WD Ultrastar HC550 16TB (~$230) — enterprise CMR

Procedure:

1. Stop array, power down
2. Swap the failed/full 8TB with the new 16TB
3. Start array → rebuild (~18-20 hrs)
4. Done — you just gained 8TB of usable space

Each time you replace an 8TB with a 16TB, your usable capacity grows:

• 1 replaced: 37.2TB usable
• 2 replaced: 45.2TB usable
• 3 replaced: 53.2TB usable
• All 4 replaced: 61.2TB usable

Drives to Recycle

Wipe before recycling if concerned about data:

Drive	Reason
Parity 1 (ZCT2K65B)	180 GP error history
Parity 2 (ZCT2K5PQ)	19 GP error history
Disk 3 (ZCT3XAEJ)	10 GP + 2 CRC + 72K load cycles

Drives to Keep as Spares

Drive	Use
Disk 4 — WD Red 4TB (WD-WCC7K2YF4TDJ)	Cold backup via USB dock. Pristine SMART. Monthly rsync of irreplaceable files (photos, documents, configs).

SMART Test Schedule (already running)

• Weekly short: Sundays 2:00 AM
• Monthly extended: 1st of month 3:00 AM
• Configured via User Scripts plugin
• Monitor results in Main → click any drive → SMART attributes

Pending Config Fixes

Can be done anytime from WebGUI, no downtime needed:

• Remove compose.manager plugin (Settings → Plugins → click X next to it)
• Disable disk shares (Settings → Global Share Settings → Enable disk shares → No)
• Set user share security to Private for exported shares (Shares → isos → SMB Security → Private; repeat for any other exported shares)
• Move domains share to cache (Shares → domains → Primary storage → Cache → Cache Pool → cache)
• Set up email notifications (Settings → Notification Settings — use Gmail + App Password)
• Configure UPS auto-shutdown (Settings → UPS Settings — CyberPower CP1500, USB, battery level 20%)
• Enable XMP in BIOS at next reboot (G.Skill DDR3 running 1333 MT/s, rated 1600 MT/s)
• Verify appdata backups work — test a restore of one container