Synology, QNAP or self-built TrueNAS for a UK small business four-bay NAS

Synology's DS925+ is the only one of these three four-bay options with ECC memory as standard, at £757.00 diskless, which matters most for financial or client records. QNAP's TS-464-8G undercuts it at £636.00, with a PCIe slot for an optional 10GbE upgrade the DS925+ lacks. A self-built TrueNAS box needs no software licence, but pricing the parts today puts it at roughly £751 diskless, so it saves nothing on hardware, only a licence fee neither Synology nor QNAP charges anyway.

Key pointers

• Synology's DS923+ has been superseded; the current four-bay Synology models are the DS425+ (budget) and DS925+ (ECC, prosumer), so check exactly which model a reseller is actually selling before you order.
• Budget £589.99 to £757.00 for the bare enclosure alone, plus £587.96 for four 4TB CMR NAS drives, whichever platform you pick.
• Only the DS925+ ships with ECC RAM as standard among the ready-built options; ask a reseller to confirm ECC support rather than assuming any Synology or QNAP box has it.
• A self-built TrueNAS box costs about the same as the DS925+ once today's DDR5 memory prices are included, so build it for TrueNAS's software, not to save money.
• Confirm your chosen drives are genuine CMR, not SMR, and check them against the vendor's compatibility list before ordering.
• Ask any reseller whether the exact model is in stock now; the DS425+ was on pre-order at the retailer checked here on 29 September 2026, not available for immediate delivery.
• QNAP's TS-464 can switch from its default QTS software to QuTS hero, which adds ZFS-based data integrity checking similar to TrueNAS, on the same hardware.
• None of these options come with a vendor support phone line if you self-build; budget time to learn TrueNAS's storage-pool setup, since there is no reseller to call.

What buying a four-bay NAS actually decides

A four-bay NAS is not extra storage bolted onto one PC; it is a small shared server that keeps working when a laptop is stolen, a desktop drive dies or ransomware hits one machine in the office. Four bays let you run the drives in a redundant layout, commonly RAID 5, Synology's SHR or a ZFS RAIDZ1, so one drive can fail without losing files while you replace it. That redundancy is not a backup on its own; you still need a second copy somewhere else, on another device or in the cloud, for the day the whole box fails.

For a small business without an in-house IT team, the real decision is not the drive bays, it is which software you want running the box for years. Synology's DSM and QNAP's QTS are polished, browser-based operating systems with wizards for shared folders, scheduled backups and drive-failure alerts; you rarely need a command line. TrueNAS, whether self-built or bought as an appliance, runs OpenZFS underneath, which checksums every block of data on write and read and catches silent corruption that a simpler filesystem would miss. The trade-off is that you assemble and support the hardware yourself, with no vendor to call when something goes wrong.

How each option gets from box to working backup

Buying Synology or QNAP means fitting drives into a sealed, purpose-built enclosure, then finishing setup entirely in a browser: the DSM or QTS wizard formats the drives into a storage pool, creates shared folders for staff and schedules a backup job such as Hyper Backup or QNAP's Hybrid Backup Sync to an external drive or cloud target. No case to build, no BIOS to configure.

Self-built TrueNAS starts a step earlier. You buy a case with hot-swap bays, a Mini-ITX motherboard with an integrated CPU and enough SATA ports, an SFX power supply, RAM and a small boot drive, then physically assemble them, much like building a small desktop PC. TrueNAS SCALE or CORE installs free from a USB stick; its own setup wizard then creates a ZFS storage pool (a mirror or RAIDZ1/RAIDZ2 layout), shared folders over SMB or NFS, and scheduled snapshots. The software cost is genuinely zero, but the assembly and pool-layout decisions land on you rather than a vendor's wizard.

Purchase price for a typical four-bay setup

Prices below are UK retail prices in pounds sterling, as displayed to a shopper on 29 September 2026; the enclosure or component prices include VAT where the retailer states so (confirmed for the case, PSU and SSD below), and drives are sold separately from every enclosure here. A typical four-bay setup means the bare unit or parts, plus four 4TB drives.

The drive line adds £146.99 x 4 = £587.96 to every option, using the WD Red Plus 4TB CMR drive price already given in Fast Facts above.

The self-build parts total comes from five separate components, none of them a single all-in-one enclosure:

That £751.01 is higher than most self-build guides assume, mainly because of the RAM line. A single 16GB DDR5 SODIMM stick ran roughly £210 to £235 in UK listings when checked, a genuinely elevated price for a memory module that would once have cost a fraction of that; the motherboard needs standard, non-ECC DDR5 for this build, and adding ECC support would mean a pricier board and CPU on top. Confirm current RAM and motherboard prices before you commit, since they move faster than enclosure prices from Synology or QNAP.

How Synology, QNAP and self-built TrueNAS compare

None of these four is a universal winner. A sole trader backing up invoices and a handful of client files has little reason to pay the DS925+'s premium over the DS425+ or a QNAP TS-464-8G. A business storing anything it cannot afford to quietly corrupt, contracts, accounts, client records, gets the clearest benefit from ECC memory, which today means either the DS925+ or a self-built TrueNAS box with a pricier ECC-capable board. Building your own only pays off if you actually want ZFS, full control over the hardware and no vendor lock-in; it does not currently pay off on price.

Editorial analysis

TrueNAS's own hardware guide is unusually candid about ECC memory: it explains that a single flipped bit in ordinary RAM can, in principle, corrupt data on its way into a ZFS pool, and that most experienced users strongly recommend ECC as a result, while also noting plenty of TrueNAS systems run for years without it. That is a more honest framing than either Synology or QNAP offers about their own non-ECC models, and it is worth taking seriously if the NAS will hold anything a business genuinely cannot afford to lose silently.

What the research does not support is the common assumption that a self-built NAS is automatically the cheap option. Once you price a real parts list, current DDR5 memory pushes a diskless self-build to roughly the same £751 as Synology's ECC-equipped DS925+, before you have bought a single drive. The honest case for self-building TrueNAS in 2026 is ZFS's data integrity and the freedom to pick your own hardware, not a lower purchase price. For a small business that wants DSM's polish and a phone number to call when a drive fails, the DS425+ or QNAP TS-464-8G both do the job at a lower entry price than either ECC-equipped route.

Sources

• DiskStation DS425+ Product Specifications, Synology
• DiskStation DS925+ Product Specifications, Synology
• TS-464 4-Bay NAS, QNAP UK store
• TS-464, Bye-bye Gigabit NAS, hello 2.5GbE NAS, QNAP
• TrueNAS Hardware Guide, iXsystems
• TrueNAS Mini, iXsystems
• Synology DiskStation DS425+ 4 Bay Desktop NAS Enclosure, Scan Computers
• Synology DiskStation DS925+ 4 bay Desktop NAS, KRCS
• Best 4TB NAS Drives UK 2026, NAS Drives UK
• Synology NAS Review UK 2026, DS225+, DS425+ and DS925+
• Jonsbo N2 Mini-ITX NAS Aluminium PC Case, Overclockers UK
• be quiet 450W SFX Power 3 PSU, Quiet PC
• Crucial P3 500GB NVMe SSD, Ebuyer
• Crucial SO-DIMM DDR5 5600MHz 16GB price comparison, PriceRunner UK