Is an all-flash NAS worth it?

For storage use at home rarely. Per usable TB HDDs are 4-6× cheaper. All-flash makes sense for VM hosting, video editing, or silent requirements.

Which SSD as NAS cache?

Read cache: consumer NVMe (WD Red SN700) is fine. Write cache: must be enterprise SSD with high TBW (Samsung PM893, Micron 7450) – consumer SSDs die in 1-2 years.

How much power does SSD save vs HDD?

Per drive in NAS 24/7: SSD saves 25-30 kWh/year = $4-7 at $0.15/kWh. Plus noise advantage and longer lifespan under normal workload.

HDD vs SSD in NAS: When Does Each Actually Pay Off?

Updated: 2026-04-29

SSDs are getting cheaper, HDDs are getting bigger. The 2026 question: does an all-flash NAS make sense or is HDD still the rational choice? Honest answer below.

Short version

Per usable TB, HDDs are 4-6× cheaper than SSDs. For pure storage HDD remains king. SSDs shine for active data, VMs, databases, and as cache. Hybrid setup (HDD pool + SSD cache) is the sweet spot for most NAS users.

Cost per TB (2026)

16 TB CMR HDD (WD Red Plus, IronWolf): ~$280 = $17.5/TB
4 TB SATA SSD (Samsung 870 QVO, WD Red SA500): ~$220 = $55/TB
8 TB SATA SSD (Samsung 870 QVO): ~$470 = $59/TB
2 TB NVMe (WD Red SN700, Samsung 990 Pro): ~$180 = $90/TB

3-5× price gap remains. Trend toward smaller gap, but no parity until 2027 at earliest.

Performance differences

Sequential read/write: SATA SSD ~550 MB/s vs HDD ~200 MB/s. Over 1 GbE (125 MB/s) or 2.5 GbE (312 MB/s) network limits, not disk. SSD advantage invisible.

Random IOPS: SSD 50,000-100,000+ vs HDD 100-200. Dramatic difference, relevant for databases, VMs, many parallel streams.

Latency: SSD <1 ms vs HDD 5-15 ms. Noticeable in web-UI snappiness and SMB browsing.

Power and noise

HDD active: 5-9 W. Idle 3-5 W. Noise 22-30 dB.
SATA SSD: 1-2 W active, 0.1-0.5 W idle. Silent.
NVMe: 4-7 W active, 1-2 W idle. Silent.

Over 5 years 24/7, an SSD per bay saves 100-150 kWh = $15-22 in power. Not trivial at 8 bays.

Lifespan reality

HDDs: 5-7 years real, AFR ~1.5% p.a. SSDs: TBW limit. A 4 TB QVO has 1,440 TBW = 720 GB/day over 5 years. In NAS with normal write load, SSD outlives HDD.

Cache SSD warning: Synology recommends only enterprise SSDs (Samsung PM series etc.) with high TBW for write cache – consumer SSDs die fast.

Hybrid: best of both

Recommended for most setups:

Main pool: 4-6 HDDs (16-22 TB) in RAID 5/6/SHR
Cache: 1-2 NVMe SSDs (1-2 TB) as read-write cache
Result: HDD capacity, near-SSD snappiness

Synology DS923+, QNAP TS-464, Ugreen DXP4800 Plus all have M.2 slots for this.

When all-flash makes sense

Small (1-4 TB) and max speed (video editing, photo workflow)
VM host (Proxmox, ESXi) – random IOPS critical
Silent operation (living room without mechanical noise)
Travel NAS / portable setups

2026 recommendation

Classic home NAS: HDD for storage + 1 NVMe as cache. All-flash only when workload justifies it or budget weights silence over capacity.

Best NAS Drives 2026

NAS power consumption

NAS noise levels

SMR vs CMR

RAID Calculator