Ultrastar DC SN drives are enterprise U.2 and U.3 NVMe SSDs, not M.2 - they need a server backplane or an adapter. The cheapest we currently track is the WUSTR1538ASS200 at $166.41/TB. Endurance is set by the exact part number, not the capacity: the SN640 ships 0.8 and 2 DWPD SKUs at the same sizes, so check the part number before you buy.
Every drive in the tables below is a 2.5-inch 15mm unit with a U.2 or U.3 connector, not the M.2 gumstick that plugs into a desktop motherboard. To use one you need a U.2 backplane, a U.2 drive bay, or a PCIe-to-U.2 adapter and a power feed. A standard desktop has none of those. The SS530 row is different again: it is a SAS SSD and needs a SAS controller, exactly like the SAS hard drives on the Ultrastar hub. Check the Form factor column on every row before ordering.
Endurance is a property of the part number, not the capacity. Where we could not source a figure for the exact SKU the cell reads unverified.
| Part number | Series | Capacity | Endurance | Interface | Form factor | Warranty |
|---|---|---|---|---|---|---|
| WUSTR1538ASS200 | Ultrastar DC SS530 | 3.84TB | 1 DWPD | SAS-12G | 2.5" | 5 yr |
| WUS4CB016D7P3E4 | Ultrastar DC SN640 | 1.6TB | 2 DWPD | NVMe-PCIe3 | U.2 | 5 yr |
| WUS5EC0C1ESP7Y3 | Ultrastar DC SN655 | 61.44TB | unverified | NVMe-PCIe4 | U.3 | 5 yr |
| WUS5EA176ESP7E1 | Ultrastar DC SN655 | 7.68TB | unverified | NVMe-PCIe4 | U.3 | 5 yr |
4 in-stock listings · ranked by live cost per terabyte
| Part number | Series | Capacity | Endurance | Cond | $/TB | Price | |
|---|---|---|---|---|---|---|---|
| WUSTR1538ASS200 | SS530 | 3.84TB | 1 DWPD | REFURB | $166.41 | $639 | Buy |
| WUS4CB016D7P3E4 | SN640 | 1.6TB | 2 DWPD | NEW | $305.63 | $489 | Buy |
| WUS5EC0C1ESP7Y3 | SN655 | 61.44TB | unverified | NEW | $1116.05 | $68570 | Buy |
| WUS5EA176ESP7E1 | SN655 | 7.68TB | unverified | NEW | $1151.02 | $8840 | Buy |
There is no capacity in this family where we currently track both a new and a refurbished listing, so there is no spread to compute. That is a fact about the market rather than a gap in the page - enterprise flash is retired on a slower cycle than hard drives and is frequently destroyed rather than resold. This block fills itself in if a second-hand track appears. The equivalent ladder for Ultrastar hard drives, where the secondary market is deep, is on the main Ultrastar page.
Ultrastar DC SN is Western Digital's enterprise NVMe solid-state line, and it is a different product category from the consumer NVMe drives most people picture when they hear the word. The physical difference is the one that catches buyers first: these are 2.5-inch, 15mm-thick units with a U.2 or U.3 connector on the back, not the M.2 gumstick that clips flat onto a desktop motherboard. They are designed to slot into a server backplane alongside hard drives, in the same bays, drawing the same power, hot-swappable in the same caddies. That is the whole design intent, and it is why a drive that looks like an obvious bargain per terabyte can be unusable in the machine you were planning to put it in.
The second difference is endurance, and it is expressed in drive writes per day: how many times over you could rewrite the drive's entire capacity, every day, for the length of the warranty, without exceeding what the manufacturer will stand behind. A consumer NVMe drive is typically rated in total terabytes written across its life, a number most desktop users never approach. An enterprise drive is rated in DWPD because the assumption is that it will be written to continuously for five years. The SN640 exists in both a 0.8 DW/D flavour and a 2 DW/D flavour, and crucially those flavours overlap in capacity — there are 1.6TB drives of each. Same line, same size, materially different drive, and the only thing that tells you which one you are looking at is the part number.
Third is power-loss protection. Enterprise drives in this class carry onboard capacitors whose job is to flush data that is in flight when the power disappears. This is the feature that makes a drive appropriate as a ZFS SLOG or a database write target, and it is the feature consumer drives generally omit. It is a design characteristic stated in the datasheets rather than something we measured, and it is the honest reason to prefer an enterprise SKU over a faster-sounding consumer one for anything that must not lose an acknowledged write.
Where this sits relative to our own categories: the broader datacenter NVMe listing lives at our U.2 category page, which tracks Micron, Samsung, Solidigm, Kioxia and Seagate alongside Western Digital. This page is the Ultrastar-specific slice of that market, kept separate because the Ultrastar part-number scheme has its own logic and because the family now spans two corporate brands.
The model name tells you the family. The part number tells you the drive. For the SN-series the pattern that matters starts WUS, and the characters that follow encode the generation, the capacity code and — the part buyers miss — the endurance and interface class. WUS4BB and WUS4CB are both SN640 part numbers; the difference between the pattern classes is not cosmetic, and the same nominal capacity can appear under either. When a reseller lists a drive as "Ultrastar DC SN640 1.6TB" and nothing more, that listing has not told you which drive it is.
This is not a pedantic distinction. The endurance rating is the single number that determines whether a drive is appropriate for a write-heavy role, and it varies by a factor of more than two within one model name at one capacity. Buying the 0.8 DW/D SKU for a workload sized around 2 DW/D means burning through the warranty envelope in well under half the intended service life. The drive will not fail on day one; it will simply exit its rated endurance early, and the warranty position at that point is exactly what the datasheet said it would be.
The practical rule is short. Find the part number in the listing title or the product images, match it against the decoder table below, and if the listing does not state a part number at all, treat the endurance as unknown rather than assuming the better of the two. We apply that rule to ourselves: rows in our own tables whose endurance we could not source for the exact SKU show "unverified" rather than a number borrowed from a sibling drive.
Port configuration follows the same logic. The SN840 line shipped in dual-port and single-port variants — dual-port being the configuration that lets two hosts reach one drive for failover in a high-availability chassis. If your chassis needs dual-port, single-port hardware will physically install and then not do the thing you bought it for. Again, the part number is what settles it.
U.2 and U.3 are connector and form-factor standards for 2.5-inch drives. They are not M.2, they are not compatible with an M.2 slot, and no amount of adapter ingenuity turns a standard consumer desktop into a sensible host for one. To run a U.2 drive you need a U.2 backplane in a server chassis, a dedicated U.2 bay, or a PCIe-card-to-U.2 adapter combined with a power connection to the drive. The adapter route works and people do it in homelabs, but it costs money, occupies a PCIe slot, and needs cabling that does not come in the box.
U.3 is the later standard and is backward-compatible in one direction only: a U.3 backplane accepts U.2 drives, while a U.2 backplane does not accept U.3 drives. That asymmetry is the one worth memorising, because it is the direction that fails. If your chassis is U.2 and the listing says U.3, that is a hardware incompatibility, not a firmware detail.
One drive in our current catalogue is a different case again. The Ultrastar DC SS530 is a SAS SSD, not NVMe: it uses the SAS interface at 12Gb/s and needs a SAS host bus adapter exactly as the SAS hard drives on our main Ultrastar hub do. It will not work on a plain SATA port, and it is not a U.2 NVMe drive despite also being a 2.5-inch enterprise SSD. The form-factor column in the tables below distinguishes all three cases on every row, and it is the first column to read.
The dual-track machinery on the rest of this site — best new price against best refurbished price, with the spread stated as a percentage — was built because enterprise hard drives have a deep and genuine secondary market. Hyperscale operators retire fleets, those drives reach resellers in volume, and the price gap between a new drive and a pulled one is real, persistent and worth quantifying. That is why the Ultrastar hub can show a new-versus-refurbished ladder at most capacities.
For Ultrastar enterprise SSDs on Amazon US, as of the most recent catalogue check, that market does not exist in any comparable form. We searched the SN640, SN655, SN840, SN861 and SA210 lines by model name and by part-number pattern. The overwhelming majority of what comes back is Ultrastar hard drives — the search matches the family name and returns HC-series spinning disks. Of the genuine enterprise SSD listings that verify as buyable, effectively all are new, and the only used one is the SAS SS530 rather than an NVMe drive. There is no capacity at which we can put a new price and a refurbished price side by side, so this page does not show a spread. An empty ladder with invented rows would be worse than no ladder.
That is a finding about this market rather than a gap in the page, and it may not stay true. Enterprise SSDs are retired from fleets on a slower cycle than hard drives and the flash that comes off them is often destroyed rather than resold for data-security reasons, which suppresses supply structurally. If a refurbished NVMe track appears, the ladder below will populate on its own — it is driven by what is in the catalogue, not by a hand-maintained list.
The prices you will see in the table are worth reading carefully for a related reason. Enterprise SSD listings on a consumer marketplace are frequently priced by third-party sellers rather than by a distributor, and a handful of the rows we track sit at costs per terabyte many times the sensible market rate. Those are flagged where our scalper heuristic catches them. A drive priced at four figures per terabyte is not a market price for that capacity; it is one seller's asking price on a listing nobody has bought.
If a used enterprise SSD does appear — here or anywhere else — the check on arrival is different from the one you would run on a hard drive, and it is not optional. A hard drive's history shows up in power-on hours and reallocated sectors. An SSD's history shows up in how much of its write endurance has already been consumed, and that figure is reported directly by the drive.
The SMART attribute to read is percentage used, exposed on NVMe drives through the standard health log and reported by smartctl as "Percentage Used". It is a wear indicator expressed against the manufacturer's rated endurance: a value of 100 means the drive has been written to the extent its rating covers. Media and data integrity errors, and the available spare figure alongside it, complete the picture. On SAS SSDs the equivalent shows up in the vendor's own wear-out indicator attributes. We are not going to tell you what threshold is acceptable, because that depends entirely on what you intend to do with the drive and there is no honest universal number — but a drive arriving with substantial consumed endurance is a drive whose remaining warranty envelope is smaller than the sticker suggests, and the seller should be telling you that figure before you buy rather than after.
The rest of the used-hardware discipline applies unchanged. Verify on arrival rather than on the strength of the listing, understand what a reseller warranty actually covers as against a manufacturer warranty, and keep the drive out of production until it has been checked. Our recertified-drive guidance and our refurbished-warranty explainer both cover that ground in detail and both apply to flash as written.
The clearest fit is somebody who already owns a server with U.2 or U.3 bays. In that case an enterprise SSD in a spare bay is straightforward: the backplane is there, the caddies are there, the power is there, and the drive slots in as designed. If that describes your hardware, the only real question is which endurance class the workload needs, which is the part-number question above.
The second group is homelab and small-scale AI builders, who arrive at these drives from a different direction. A ZFS pool wants a fast, power-loss-protected device for its intent log, and an inference rig wants storage that can feed model weights without becoming the bottleneck — both are roles where enterprise flash with capacitors is genuinely the right component rather than an indulgence. The cost of entry is the adapter and the slot, and that cost is worth weighing against a consumer drive with power-loss protection where one exists. Our budget inference build guide and our enterprise SSD NAS page both work through that trade-off with live pricing.
The group these drives are not for is anyone hoping to add fast storage to an ordinary desktop. A consumer M.2 NVMe drive is the correct component for that job — it is cheaper per terabyte at consumer capacities, it needs no adapter, and the endurance advantage of an enterprise drive is irrelevant to a workload that writes a few terabytes a year. Buying a U.2 enterprise drive for a gaming PC means paying an enterprise premium for capacitors you will not use and then paying again for the adapter to make it fit.
If you have noticed that some of these listings say Western Digital and others say SanDisk for what is visibly the same product family, that is not a counterfeit signal. Western Digital separated its hard-drive and flash businesses into two independent public companies in 2025: the HDD business kept the Western Digital name, and the flash and SSD business — which had held the SanDisk brand since Western Digital acquired it — became SanDisk again as a standalone company. The Ultrastar DC SSD lines went with the flash side.
For a buyer the practical consequences are small but worth knowing. The drives themselves are unchanged, part numbers are unchanged, and a WUS-prefixed SN655 is the same drive whichever logo is on the listing. What does shift is where support and documentation live, and which company's warranty process you are dealing with. Listings created before and after the separation coexist on the marketplace, which is why our own catalogue carries the same series under two brand names. The main Ultrastar hub carries a fuller account of the split.
Almost certainly not without extra hardware. U.2 and U.3 are 2.5-inch server form factors, not the M.2 slot on a desktop motherboard. You need a U.2 backplane, a dedicated U.2 bay, or a PCIe-to-U.2 adapter card plus a power connection to the drive. If you are adding storage to an ordinary desktop, a consumer M.2 NVMe drive is the right component and will cost less per terabyte at consumer capacities.
Drive writes per day: how many times the drive's full capacity you could write, every day, across the warranty period, within what the manufacturer will stand behind. A 0.8 DWPD 1.6TB drive is rated for roughly 1.28TB of writes per day for five years. It is an endurance rating, not a speed rating, and it is set per part number rather than per capacity — the SN640 ships both 0.8 DW/D and 2 DW/D SKUs at the same sizes.
They can be, but the check is different from a hard drive. Read the SMART percentage-used attribute on arrival — on NVMe it comes from the standard health log and smartctl reports it directly — along with available spare and media error counts. That figure tells you how much of the drive's rated write endurance has already been consumed. What counts as acceptable depends on your workload, so we do not publish a threshold, but a seller who cannot tell you the figure before purchase is asking you to buy blind.
Western Digital split into two companies in 2025. The hard-drive business kept the Western Digital name; the flash and SSD business became SanDisk as an independent company, taking the Ultrastar DC SSD lines with it. The drives, the part numbers and the specifications are unchanged — only the branding on newer listings and the support destination differ.
U.3 is the later standard and the compatibility runs one way: a U.3 backplane will accept U.2 drives, but a U.2 backplane will not accept U.3 drives. If your chassis is U.2 and the drive is U.3, that is a hardware incompatibility. Check which one your backplane is before ordering, because this is the direction that fails.
No. The Ultrastar DC SS530 is a SAS SSD, not NVMe. It uses a 12Gb/s SAS interface and needs a SAS host bus adapter, exactly like the SAS hard drives on our main Ultrastar page. It will not run from a plain SATA port and it is not a U.2 NVMe drive, despite also being a 2.5-inch enterprise SSD. The form-factor column on every table row distinguishes the two.
Because that is what verifies. We searched the SN640, SN655, SN840, SN861 and SA210 lines by model name and by part-number pattern, and most of what a marketplace search returns for these terms is Ultrastar hard drives rather than SSDs. The genuinely buyable enterprise SSD listings are few, and almost all are new — unlike enterprise hard drives, there is essentially no refurbished NVMe market here. We list what we can verify rather than padding the table.
Specification claims on this page were checked against the pages below on 4 August 2026. Where a widely-repeated figure did not survive that check, we report what the source says now and say so in the text rather than repeating the familiar number.