Quick Answer

Building a 100TB NAS in 2025 is easier and cheaper than ever. Here’s what you need:

• Operating System: TrueNAS SCALE (Linux-based, Docker support, actively developed)
• Drives: Eight 18-22TB CMR enterprise drives (Seagate Exos X20, WD Ultrastar HC560, or Toshiba MG series)
• Motherboard: Supermicro X12STH-F with IPMI, 8 SATA ports, and ECC support
• CPU: Intel Xeon E-2300 series or AMD Ryzen 5 5600G
• RAM: 32-64GB ECC DDR4
• HBA: Broadcom LSI 9300-8i flashed to IT mode
• Network: 10GbE SFP+ for serious throughput
• Total Cost: Around $2,500-3,500 for 100TB usable storage

This build costs roughly $2,500 upfront and saves you thousands compared to cloud storage or pre-built NAS boxes over five years.

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Why Build a 100TB NAS?

Data is exploding everywhere. 4K video editing, high-resolution photography, AI projects, and home lab experiments all need massive storage. Cloud storage seems convenient, but the math doesn’t work out:

• 100TB on Backblaze B2 at $5/TB/month = $6,000+ over five years
• Plus egress fees every time you download your own data
• Plus trusting your data to someone else’s servers

Consumer NAS boxes from Synology or QNAP top out at 8-12 drive bays and get expensive fast. Enterprise solutions from NetApp work great but cost more than a car.

A DIY NAS with TrueNAS gives you enterprise-grade ZFS reliability at a fraction of the cost. You control the hardware, security, and upgrades.

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Cost Comparison: DIY vs Pre-built vs Cloud

Option	Upfront Cost	Drive Bays	5-Year Total Cost	Best For
DIY NAS	$2,500-3,000	8-12+	~$2,500-3,500	Maximum flexibility, power users
Synology/QNAP	$2,000-3,000 + drives	8-12	~$4,000-5,000	Easy setup, limited expansion
Cloud (B2, Wasabi)	None	Unlimited	$6,000-8,000	Pay-as-you-go, slower restores

Assumes $0.15/kWh electricity and no drive replacements. DIY wins on cost and flexibility.

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When Does 100TB Make Sense?

A 100TB pool makes sense if you:

• Work with terabytes of raw video footage regularly
• Store large research datasets or AI training data
• Consolidate family photo backups, Plex libraries, and VM storage
• Need plenty of room for snapshot history and off-site replication

If your needs are under 20TB, a simple 2-4 bay Synology or single RAIDZ1 vdev works fine. Don’t overbuild.

Important: Once you create a ZFS pool, you can’t remove vdevs. Plan for growth from the start. OpenZFS 2.3 now supports RAIDZ expansion, but it’s still new—adding new vdevs or replacing drives remains the proven method.

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Hardware Selection Guide

Your hardware choices determine reliability, performance, and longevity. Here’s what to pick in 2025.

CPU Options

Category	Examples	TDP	ECC Support	Best For
Low Power	Intel N100, AMD Mendocino	6-9W	No	Basic file sharing, light Plex
Mainstream	AMD Ryzen 5 5600G, Intel i3-12100	65W	Ryzen Pro: Yes	Docker, moderate VM use
Server Grade	Xeon E-2324G, AMD EPYC 7232P	65-120W	Yes	Heavy virtualization, mission-critical

Sweet Spot: AMD Ryzen 5 5600G costs around $150-180, offers 6 cores/12 threads, and Ryzen Pro models support ECC RAM. For remote management (IPMI), go with Xeon E-2300 series.

Motherboard Features to Look For

The Supermicro X12STH-F remains the community favorite:

Feature	Supermicro X12STH-F	ASUS ProArt B760I	ASRock N100M
Socket	LGA 1200 (Xeon)	LGA 1700	Integrated N100
SATA Ports	8	4	4-6
ECC Support	Yes	No	No
IPMI	Yes (AST2600)	No	No
10GbE	No (upgrade slot)	No	No
Price	~$350	~$150	~$150

IPMI gives you out-of-band access—power cycling and console without a monitor. Essential for headless servers.

Memory: ECC vs Non-ECC

ECC memory corrects single-bit errors and protects against undetected corruption. Strongly recommended for ZFS, but not mandatory.

• 32GB: Basic file serving
• 64GB: VMs and L2ARC caching
• 128GB: Heavy virtualization workloads

The old “1GB RAM per TB” rule is outdated. ZFS uses ARC (adaptive replacement cache) efficiently. 32-64GB works fine for 100TB pools without heavy VM workloads.

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Hard Drive Selection

Drives are the heart of your NAS. Get this right.

CMR vs SMR: Why It Matters

Feature	CMR (Conventional)	SMR (Shingled)
Write Speed	Consistent	Slows under load
RAID Rebuilds	Fast and reliable	Slow, can fail
NAS Use	Recommended	Avoid
Typical Use	24/7 enterprise workloads	Cold archives only

SMR drives write overlapping tracks like shingles on a roof. This saves manufacturing costs but kills performance under sustained writes—exactly what happens during RAID rebuilds. Avoid SMR for NAS.

Best 18-22TB Enterprise Drives (2025)

Drive	Capacity	Key Specs	Price	Cost/TB
Seagate Exos X20	20TB	CMR, 2.5M hr MTBF, 5-year warranty	~$330	~$16.50
WD Ultrastar HC560	20TB	CMR, OptiNAND, 2.5M hr MTBF	~$340	~$17
Toshiba MG10	18-22TB	CMR, 550TB/year workload, helium	~$320-350	~$16-17

All three are enterprise-class with 5-year warranties and 2.5 million hour MTBF ratings.

Shucking: Cheaper Drives, More Risk

“Shucking” means buying external USB drives and removing the internal drive. In 2025, 18-20TB WD Elements or Seagate Expansion enclosures sometimes sell for $280-300—about $14-15 per TB.

Risks:

• Voids warranty
• Some contain SMR drives (check model numbers before buying)
• 3.3V pin issue on some WD drives (tape fix required)

For 100TB: Eight 20TB drives cost roughly $2,400 at ~$300 each.

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Cases: Your Enclosure Options

Case	Form Factor	Drive Bays	Highlights	Price
Fractal Define 7 XL	Full Tower	Up to 18 × 3.5"	Sound-damped, modular, E-ATX support	~$200
SilverStone CS381	Micro-ATX Cube	8 hot-swap	Dual orientation, SFX PSU support	~$250
Fractal Node 804	Micro-ATX Cube	10 × 3.5"	Dual-chamber, great airflow, budget	~$150
Supermicro 4U SC846	Rack Mount	24 hot-swap	Professional, front-loading SAS backplane	~$500+

Recommendation: Pick a case with more bays than you need now. Future drive upgrades need space. Hot-swap trays make replacements painless.

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HBA and SATA Expansion

Most motherboards provide only 6-8 SATA ports. Host Bus Adapters (HBAs) add more.

The Gold Standard: LSI 9300-8i

Spec	Details
Controller	SAS3008
Ports	8 × 12Gb/s SAS/SATA
Interface	PCIe 3.0 ×8
Max Devices	1,024
Price	~$160 used

Critical: Flash the firmware to IT mode for ZFS passthrough. The r/DataHoarder wiki has cross-flash instructions. RAID mode causes problems with ZFS.

For 16+ drives: Use two HBAs or the LSI 9400-16i (PCIe 4.0, 16 ports).

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Power Supply and UPS

PSU Sizing

Each 3.5" drive draws roughly 25W at spin-up and 8W during operation. Calculate your needs:

Component	Power Draw
8 × 20TB drives (spin-up)	~200W
Motherboard + CPU (65W TDP)	~90W
HBA + NIC + fans	~30W
Total Peak	~320W

Recommendation: 500W 80 Plus Gold PSU gives 25% headroom and efficient operation. Seasonic, Corsair, and Supermicro make reliable units around $90-100.

UPS Requirements

Power failures corrupt ZFS transactions. Always use a UPS.

Your Load	Minimum UPS Rating	Recommended
250W	500VA (borderline)	800-1000VA
350W	700VA (minimum)	1000-1500VA

APC, CyberPower, and Eaton line-interactive models protect against brownouts. Connect via USB to TrueNAS and enable automatic shutdown when battery drops low.

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TrueNAS: SCALE vs CORE

TrueNAS comes in two flavors. In 2025, the choice is clear.

Feature	TrueNAS CORE 13.x	TrueNAS SCALE (Community Edition)
Base OS	FreeBSD	Debian Linux
Status	Maintenance only, security patches	Active development
Apps	Jails, Bhyve VMs (deprecated)	Docker, Kubernetes (K3s)
File Protocols	SMB, NFS, iSCSI, WebDAV, AFP	SMB, NFS, iSCSI
Virtualization	Bhyve	KVM, GPU passthrough
OpenZFS Version	2.2 (frozen)	2.3 (latest features)

When to Choose SCALE (Almost Always)

• New builds
• Docker and container workloads
• GPU passthrough for Plex transcoding
• RAIDZ expansion (OpenZFS 2.3)
• Better hardware compatibility
• Active development and new features

When to Consider CORE

• Existing FreeBSD jail workflows
• Legacy enterprise environments certified on FreeBSD
• Extreme stability requirements (but SCALE is now mature)

Bottom Line: TrueNAS CORE is in long-term support only. TrueNAS SCALE is the future. iXsystems is unifying both into TrueNAS Community Edition with the 25.04 “Fangtooth” release.

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ZFS Pool Configuration

ZFS protects data using vdevs (virtual devices) in different RAID configurations. Your choice balances capacity, performance, and reliability.

RAIDZ Levels Compared

Level	Parity Drives	Survives	Performance	Space Efficiency
RAIDZ1	1	1 failure	Good	75-87% (3-8 disks)
RAIDZ2	2	2 failures	Moderate	67-80% (4-10 disks)
RAIDZ3	3	3 failures	Lower	60-75% (5-12 disks)
Mirror	N/A (copies)	Half drives	Best	50%

Why Wide RAIDZ Is Dangerous

Rebuilding large drives takes hours or days. During rebuild, all remaining drives are stressed. With 20TB drives, a second failure during rebuild is catastrophic with RAIDZ1.

Recommendations:

• RAIDZ1: Only for 3-4 small drives or cold archives
• RAIDZ2: 4-6 drives per vdev (sweet spot)
• RAIDZ3: 7-9 drives per vdev
• Mirrors: Best IOPS, fastest resilver, easiest expansion

Recommended Configurations for 100TB

Configuration	Drives	Usable Space	Best For
Two 4-drive RAIDZ2 vdevs	8	~80TB	Balanced workloads
Two 6-drive RAIDZ2 vdevs	12	~160TB	Higher capacity
Four 2-drive mirrors	8	~80TB	VMs, databases, high IOPS
Three 3-drive mirrors	9	~60TB	Maximum redundancy

Dataset Best Practices

Create separate datasets for different workloads:

• /tank/media - Movies, TV shows (recordsize=1M)
• /tank/backups - Backup targets
• /tank/vms - Virtual machines (recordsize=16K)
• /tank/apps - Docker volumes

Each dataset gets independent quotas, compression settings, and snapshot policies.

Compression: LZ4 vs Zstd

Algorithm	Speed	Compression Ratio	Best For
LZ4	Very fast	Good (2-3x typical)	Default for everything
Zstd	Fast	Better (3-5x)	Archival, backups

Enable compression on all datasets. Modern CPUs handle the overhead easily, and you get free space savings.

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Caching: ARC, L2ARC, and SLOG

ARC (In-RAM Cache)

ZFS caches frequently accessed data in RAM automatically. More RAM = better performance. This is your primary cache.

L2ARC (SSD Cache)

Extends ARC onto an SSD. Only add L2ARC after maxing out RAM—it’s less effective and consumes RAM for metadata.

SLOG (Sync Write Log)

Stores the ZFS Intent Log for synchronous writes. Improves small-block write latency and protects against power loss.

Requirements for SLOG:

• High-endurance NVMe or Optane
• Power-loss protection (critical!)
• Mirror for redundancy

Special VDEV

OpenZFS 2.1+ supports a special vdev: a dedicated SSD pool for metadata and small files. Speeds up directory listings and searches dramatically for pools with millions of files.

Warning: The special vdev must have the same (or better) redundancy as your main pool. Losing it destroys the entire pool.

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Network Architecture

Why Gigabit Isn’t Enough Anymore

Gigabit Ethernet maxes out at ~110MB/s. A single 20TB drive can sustain 250MB/s. Your network becomes the bottleneck.

Speed	Max Throughput	100GB Transfer Time
1 GbE	~110 MB/s	15-20 minutes
2.5 GbE	~280 MB/s	6-8 minutes
10 GbE	~1,100 MB/s	~90 seconds

10GbE Options Compared

Type	Latency	Power	Cable Type	Price
SFP+ DAC	~300ns	~0.7W/port	Copper (up to 5m)	~$15
SFP+ Fiber	~300ns	~1W/port	LC multi-mode (up to 300m)	~$50
10GBASE-T RJ45	~2.6µs	~2.5W/port	Cat6a (up to 100m)	~$100

Recommendation: Intel X520-DA2 or Mellanox ConnectX-3/4 for SFP+. Use DAC cables for short runs (under 5m). RJ45 10GBASE-T works but runs hotter.

Switch Recommendations

Switch	Ports	Uplinks	Features	Price
MikroTik CRS305	4 × 10GbE SFP+	—	Basic, affordable	~$140
QNAP QSW-M2108-2C	8 × 2.5GbE	2 × 10GbE	Managed, VLAN	~$250
TP-Link TL-SX1008	8 × 10GbE	—	Unmanaged, copper	~$400

For most home labs: 2.5GbE for clients, 10GbE uplink between NAS and switch.

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Essential Services Setup

SMB Shares

1. Create a dataset per share (media, photos, backups)
2. Enable Windows-compatible ACLs
3. Disable guest access
4. Create users and groups with appropriate permissions
5. Enable Recycle Bin for personal files (disable for backups)

Snapshot Automation

Snapshots capture dataset state at a point in time. Perfect for recovering from ransomware or accidental deletions.

Problem: Hourly snapshots = 2,232 snapshots in 9 weeks.

Solution: Use tiered retention:

• 24 hourly snapshots (last day)
• 30 daily snapshots (last month)
• 3 monthly snapshots

Total: 57 snapshots cover 3 months.

Backup Strategy: 3-2-1 Rule

Keep three copies of data, on two different media, with one off-site.

Backup Target	Method	Cost	Best For
Secondary NAS	ZFS replication	Hardware cost	Fast local restore
Cloud (B2/Wasabi)	Cloud Sync	~$5/TB/month	Off-site, irreplaceable data
Remote Server	`zfs send	zfs recv`	Varies

Monitoring

Enable these in TrueNAS:

• SMART monitoring for all drives
• Monthly ZFS scrubs (catches silent corruption)
• Email alerts for pool degradation or high temps
• UPS daemon with automatic shutdown

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Sample Builds with Pricing

100TB Build (~$2,500)

Component	Model	Qty	Price	Subtotal
CPU	AMD Ryzen 5 5600G	1	$170	$170
Motherboard	Supermicro X12STH-F	1	$350	$350
RAM	2 × 16GB DDR4 ECC	1 set	$140	$140
Storage	Seagate Exos X20 20TB	5	$330	$1,650
HBA	LSI 9300-8i (IT mode)	1	$160	$160
PSU	Seasonic Focus GX-550	1	$90	$90
Case	Fractal Node 804	1	$150	$150
NIC	Intel X520-DA2 10GbE	1	$80	$80
Misc	Fans, cables, UPS	—	$200	$200
Total				~$2,540

Five drives as two mirrored pairs + spare = ~80TB usable. Upgrade to eight drives for full 100TB.

150TB Build (~$3,500)

Component	Model	Qty	Price	Subtotal
CPU	Intel Xeon E-2324G	1	$350	$350
Motherboard	Supermicro X12STH-F	1	$350	$350
RAM	4 × 16GB DDR4 ECC	1 set	$280	$280
Storage	WD Ultrastar HC560 20TB	8	$340	$2,720
HBA	LSI 9300-8i	1	$160	$160
PSU	Corsair RM650x Gold	1	$110	$110
Case	Fractal Define 7 XL	1	$200	$200
NIC	Mellanox ConnectX-4 Lx	1	$150	$150
UPS	APC BX1500M (1500VA)	1	$200	$200
Total				~$3,520

Eight drives as two 6-drive RAIDZ2 vdevs = ~120TB usable.

200TB Build (~$7,700)

Component	Model	Qty	Price	Subtotal
CPU	AMD EPYC 7232P	1	$400	$400
Motherboard	ASRock Rack SPC621D8	1	$600	$600
RAM	128GB ECC RDIMM	1 set	$600	$600
Storage	Toshiba MG10 20TB	12	$330	$3,960
HBA	LSI 9400-16i (PCIe 4.0)	1	$300	$300
PSU	Seasonic PRIME PX-1000	1	$230	$230
Case	Supermicro 4U SC846	1	$600	$600
NIC	Intel X710-DA4	1	$300	$300
UPS	Eaton 9PX 3000VA	1	$700	$700
Total				~$7,690

Twelve drives as two 6-drive RAIDZ2 vdevs = ~160TB usable. Room for 12 more drives.

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Common Mistakes to Avoid

1. Mixing drive sizes or SMR/CMR: ZFS limits capacity to the smallest drive in a vdev
2. Under-sizing PSU: Boot failures happen when PSU can’t handle spin-up current
3. Skipping ECC RAM: Not mandatory, but reduces silent corruption risk
4. No backups: ZFS is not a backup—use replication or cloud sync
5. Too-wide RAIDZ vdevs: Stay at 4-6 drives per vdev for reasonable rebuild times
6. Poor cooling: Drives need airflow—high temps shorten lifespan
7. No expansion planning: Start with more bays than you need

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Future-Proofing Your Build

OpenZFS 2.3 RAIDZ Expansion

Available now in TrueNAS 25.04 “Fangtooth”. Add drives to existing RAIDZ vdevs one at a time. Game-changer for home users, but the rebalancing process takes days on large pools.

Drive Upgrade Path

Replace drives gradually:

1. Buy larger drive pair
2. Mirror them and resilver
3. Retire smallest pair
4. Repeat every 2 years

This expands capacity while refreshing warranties.

Network Evolution

25GbE is coming to consumer pricing. Many new NICs support 25GbE at costs similar to 10GbE. Plan PCIe slots and cabling for future upgrades.

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Worked Example: 100TB Plex + VM Server

A content creator wants 100TB usable, quiet operation, and future expansion for a Plex library and KVM virtual machines.

Hardware Selection:

• Case: Fractal Define 7 XL (18 bays, sound-damped)
• PSU: Seasonic Focus GX-650 Gold
• Motherboard: Supermicro X12STH-F + Xeon E-2346G
• RAM: 64GB ECC DDR4
• Storage: 8 × Seagate Exos X20 20TB (two 6-drive RAIDZ2 vdevs)
• Cache: 2 × Samsung 870 QVO 4TB as mirrored special vdev
• SLOG: Intel Optane P4801X 100GB
• Network: Intel X520-DA2 10GbE + MikroTik CRS305 switch

Software Configuration:

1. Install TrueNAS SCALE
2. Create pool with two RAIDZ2 vdevs + mirrored special vdev
3. Enable LZ4 compression
4. Create datasets: Plex, VMs, Backups
5. Deploy Plex via Docker
6. Configure GPU passthrough for transcoding
7. Set up hourly/daily/monthly snapshots
8. Replicate to Backblaze B2

Cost: ~$4,000 including UPS. Enterprise reliability, 10GbE throughput, room for 10+ more drives.

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Final Checklist

• Define requirements (current + 5-year growth)
• Select hardware (favor ECC memory and IPMI)
• Plan network (2.5GbE minimum, 10GbE recommended)
• Assemble and burn-in (memtest + drive tests for 24+ hours)
• Install TrueNAS SCALE
• Configure pool and datasets
• Set up users, shares, and snapshots
• Implement off-site backup
• Enable monitoring and alerts
• Keep at least one cold spare drive

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Sources and References

1. TrueNAS Scale vs TrueNAS Core - XDA Developers
2. CMR vs SMR: What’s the Difference - SecureDataRecovery
3. Supermicro X12STH-F Specifications
4. Best CPU for NAS 2025 - LincPlus Tech
5. LSI SAS 9300-8i Review - StorageReview
6. Power Supply Sizing - TrueNAS Community
7. UPS Guide for NAS - NAS Compares
8. 10GBASE-T vs SFP+ Comparison - FS.com
9. OpenZFS Snapshots Best Practices - Klara Systems
10. TrueNAS Hardware Guide - TrueNAS Docs
11. Best Hard Drives 2025 - Tom’s Hardware
12. Seagate Exos X20 Specifications
13. WD Ultrastar DC HC560 - Western Digital
14. Toshiba MG Series Enterprise Drives
15. Fractal Define 7 XL Specifications
16. SilverStone CS381 Specifications
17. Fractal Node 804 Specifications
18. 80 Plus Certification Explained - Seasonic
19. Mirror vs RAIDZ - JRS Systems
20. ZFS Pool Layout Guide - Klara Systems
21. ZFS Compression with LZ4 - QuestDB
22. ZFS Caching Explained - 45Drives
23. OpenZFS vdev Types - Klara Systems
24. Home Lab Network Upgrades 2025 - Virtualization Howto
25. OpenZFS 2.3 RAIDZ Expansion - The Register
26. TrueNAS Fangtooth OpenZFS 2.3 - TrueNAS Blog
27. TrueNAS Core vs Scale Comparison - WunderTech
28. WD Ultrastar HC560 Review - NAS Compares