Key Facts: NAS & Homelab Storage
This page is NAS Lab's maintained fact reference — the specification and marketing-decode facts our guides are built on, restated in plain prose. Figures are typical ranges and are labeled as approximate where appropriate; we report specs and general concepts, never a guarantee about your data.
RAID is not a backup
RAID (except RAID 0) protects against a single drive failing — the array stays online while you replace the disk. It does nothing against accidental deletion, ransomware, corruption, a failed controller, theft, fire, or a power surge, all of which hit the live array and every mirror at once. RAID is about uptime and availability; a backup is a separate, ideally offline or off-site copy you can restore from. You need both. See RAID Is Not Backup.
The 3-2-1 backup rule
Keep at least 3 copies of your data, on 2 different media types, with 1 copy off-site. A single RAID NAS satisfies none of the three on its own. A practical home version: files on your PC, a copy on the NAS, and an off-site or cloud copy — and test a restore occasionally. See The 3-2-1 Backup Rule.
SHR vs classic RAID
SHR (Synology Hybrid RAID) lets you mix different-sized drives and still use most of the space, and grow by swapping in bigger disks one at a time; classic RAID (1/5/6/10) generally limits every drive to the size of the smallest. SHR gives the same redundancy as RAID 1 or RAID 6 (SHR-2) with more flexible expansion, but it's Synology-specific. See SHR vs Classic RAID.
CMR vs SMR drives
NAS-rated drives use CMR (conventional) recording; many cheap desktop/external drives use SMR (shingled), which must rewrite whole zones on write and is slow under sustained load. In a RAID rebuild an SMR drive can crawl or drop out, risking a second failure. Use CMR NAS drives (WD Red Plus, Seagate IronWolf); the plain WD Red was infamously SMR — confirm CMR on the spec sheet. See CMR vs SMR Drives.
Why 2.5GbE matters (the 1GbE ceiling)
A 1GbE link tops out around 110–118MB/s of real throughput, but a single modern hard drive already reads at roughly 180–280MB/s — so gigabit throttles the drive by about half, and an array or NVMe cache far more. 2.5GbE lifts the ceiling to ~280MB/s, roughly one fast HDD; 10GbE only pays off with NVMe pools or big arrays. See 2.5GbE vs 1GbE.
ECC RAM: nice, not mandatory at home
ECC memory corrects single-bit RAM errors and is reassuring on always-on systems with lots of RAM and irreplaceable data — but it is not required for a home NAS. The "ZFS needs ECC or it destroys your data" claim is a myth: ZFS is safer with ECC yet doesn't require it. A tested backup protects your data far more than ECC does. See ECC RAM: The Truth.
RAM upgrade reality by model class
Entry boxes (like the Synology DS224+) often have a small soldered amount plus one SODIMM slot with a modest official maximum (~6GB). Mid boxes (QNAP TS-x64, TerraMaster, UGREEN) usually take one DDR4/DDR5 SODIMM up to 16GB, and prosumer boxes like the DS923+ reach 32GB of ECC. More RAM helps caching, many apps, containers, and VMs — not raw single-user file speed. Confirm the official maximum before buying.
Docker/VM capability thresholds
The x86 Celeron/N-series and low-power AMD chips in these boxes run a handful of lightweight Docker containers with 4–8GB RAM comfortably; full VMs or many heavy containers want a stronger CPU and 8–16GB+. ARM-based budget NAS units and some entry models can't run VMs or full container platforms at all — for self-hosting, prioritize an x86 NAS with expandable RAM. See NAS Docker & VM Guide.
Drive-failure framing
Drives fail, but at low, plannable rates. Backblaze's large-scale published drive-reliability reports show annualized failure rates that are typically in the low single-digit percentages, varying by model and age, and clustering early ("infant mortality") and again in old age. Buy NAS-rated drives, consider mixing batches, replace failures promptly, keep a real backup, and consider two-drive redundancy (RAID 6 / SHR-2) on larger arrays.
The Synology drive-compatibility situation
Synology has progressively pushed its Plus-series boxes toward its own-branded drives: NVMe storage pools and some features have long expected Synology SSDs, and with the 2025 Plus generation (e.g. DS925+) Synology moved to enforce a verified-drive list for full functionality, restricting or warning against third-party drives. Older Plus models (DS923+, DS224+) are more permissive but still publish a compatibility list. Always check the exact model's current, dated policy. See Synology Drive Lock.
DIY (TrueNAS) vs turnkey
Turnkey units give polished software, apps, easy setup, low power, and vendor support, at the cost of weaker hardware-per-dollar and lock-in. DIY (TrueNAS/Unraid on a mini PC or built box) gives far more CPU/RAM per dollar, ZFS on your terms, and no drive lock-in, at the cost of doing your own integration and updates. Buy turnkey for an appliance; go DIY if the homelab is the hobby. See DIY TrueNAS vs Synology.
Power consumption & electricity cost (estimates)
A typical 2-bay NAS idles around 8–15W and pulls roughly 20–35W with two active hard drives; a 4-bay runs higher, very roughly 25–50W in normal use and more during a rebuild, with each 3.5" drive adding about 4–8W. As a rough estimate, a box averaging 30W running continuously uses about 260kWh/year — on the order of a few dozen dollars a year near a US average rate, varying widely by your electricity rate and drive count. These are estimates, not product prices. See Power Consumption Truth.
How these facts are maintained
These facts are drawn from manufacturer specifications, published storage and filesystem engineering, and public reliability data (e.g. Backblaze drive-stats reports), reviewed against our guides and updated on the date shown above when the market changes. We do not publish prices or star ratings, every pick names an honest drawback, and we report specifications and general concepts — never a guarantee about your data. Our full methodology is at How We Evaluate NAS & Homelab Storage.