Western Digital Ultrastar DC SN840 6.4TB PCI Express NVMe 3.0 x4 2.5" U.2 SFF Enterprise Solid State Drive

Where the Ultrastar DC SN840 6.4TB is deployed

• Write-heavy tiers: logging, journals and checkpoint targets
• Capacity expansion into free 2.5" U.2 SFF bays
• Like-for-like replacement and spares holding for deployed fleets
• New build-outs standardised on PCI Express NVMe 3.0 x4

Questions buyers ask about this part

Will the 6.4TB Ultrastar DC SN840 fit my server?

This is a 2.5" U.2 SFF part on PCI Express NVMe 3.0 x4. It fits any bay wired for PCI Express NVMe 3.0 x4 with dual-port SAS routing. Send us your server model and we will confirm backplane support, firmware level and any bracket or caddy required before you order — that check is part of every order we ship.

What is the endurance rating on the 6.4TB?

3 DWPD (mixed use). Across 6.4TB of capacity that is approximately 35 PB of total writes over a five-year term, calculated from the drive-writes-per-day rating. Compare that against your workload's measured daily write volume: if you are writing more than 19TB a day to a single drive, ask us about the mixed-use alternatives instead.

Should I take the 6.4TB or the 15.36TB?

They are the same drive with different capacity: identical PCI Express NVMe 3.0 x4, 2.5" U.2 SFF and endurance rating. The 15.36TB gives you 2.4x the capacity per bay. Where bays are the constraint — a full backplane, or a rack you cannot grow — the larger capacity is usually cheaper per usable terabyte once you count the chassis it saves. Ask us for both on one quote and compare.

How fast is the 6.4TB Ultrastar DC SN840?

Up to 3,200 MB/s sequential read and up to 2,000 MB/s sequential write, which is what PCI Express NVMe 3.0 x4 allows. Sustained figures under a real mixed workload land lower than the sequential headline — tell us your access pattern and queue depth and we will tell you what to expect rather than quoting the datasheet at you.

Is this Western Digital part genuine, and is the warranty intact?

Yes. We supply through authorized distribution only, so the part carries the full Western Digital manufacturer warranty and its firmware update path stays supported. No grey-market stock, no re-labelled drives, no voided warranties.

Do you offer volume pricing and accept purchase orders?

The listed price is per unit and indicative; tiered pricing applies at quantity. We accept purchase orders from qualified businesses, government and defence agencies, and educational institutions, with net terms and consolidated invoicing available. Email the quantity you need and we will come back within 48 business hours.