Pick Between WD Ultrastar and Seagate Exos
Two data-centre ranges that are level on paper and differ on price and stock
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WD Ultrastar and Seagate Exos are the two data-centre drive ranges that home NAS builders buy for capacity, and on their makers' data sheets they are level: 2.5 million hours MTBF and a 5-year limited warranty on both. WD states a 550TB-a-year workload in its Ultrastar DC HC580 and HC590 data sheets; Seagate's Exos data sheets state none, though its Exos X24 product manual gives under 550TB a year. So the choice comes down to price per terabyte, condition and capacity: Exos reaches 32TB in Seagate's data sheets and the largest CMR Ultrastar is 26TB.
Ultrastar vs Exos, from the data sheets
| WD Ultrastar DC HC580 / HC590 | Seagate Exos | |
|---|---|---|
| MTBF | Up to 2.5 million hours (projected) | 2.5 million hours |
| Limited warranty | 5 years | 5 years |
| Workload in the data sheet | 550TB a year | Not stated |
| Workload elsewhere | Same as the data sheet | Under 550TB a year in the Exos X24 product manual (12TB, 16TB, 20TB, 24TB models) |
| Largest capacity in the data sheets read | 26TB (HC590, CMR) | 32TB |
| Spindle speed | 7200 RPM | 7200 RPM |
Where the figures come from
Western Digital's data sheets for the Ultrastar DC HC580 and HC590, and Seagate's Exos data sheets and Exos X24 product manual, read on October 12, 2026. Older models of both ranges, which make up most recertified stock, have their own data sheets and are not restated here.
Checked on October 12, 2026. Sources: Western Digital: Ultrastar DC HC580 data sheet; Western Digital: Ultrastar DC HC590 data sheet; Seagate Exos data sheet DS2045.4-2511; Seagate Exos data sheet DS2080-2307; Seagate Exos X24 SATA Product Manual, publication 205194300, Rev. A; Seagate Exos data sheet DS2045.4-2106; Seagate Exos data sheet DS2011.1-1904.
Condition matters more than brand here
Both ranges are sold new, renewed and used on Amazon.com, and the recertified market for each is large. The 5-year warranty in the data sheets applies to a new drive. A renewed or used listing carries whatever cover the seller states, so two listings of the same model can be very different purchases.
Both ranges also come with SATA and with SAS interfaces. A desktop NAS needs SATA; the interface is in the listing title.
Each range in full
Ratings by model number and the full live tables are on the range pages.
WD Ultrastar, by price per TB
Seagate Exos, by price per TB
Renewed, refurbished and used listings
Shown for reference. These are not counted in the best price per TB above, and warranty terms differ from new drives.
Frequently asked questions
Is Ultrastar or Exos more reliable on paper?
Their makers give the same figures: 2.5 million hours MTBF and a 5-year limited warranty. Those are specifications, not field failure rates.
Which goes larger?
Exos, to 32TB in the Seagate data sheets we read. The largest CMR Ultrastar is the 26TB DC HC590.
Does either state a workload limit?
WD states 550TB a year in the Ultrastar DC HC580 and HC590 data sheets. Seagate's Exos data sheets do not state one; its Exos X24 product manual gives a maximum of under 550TB a year.