Ultrastar vs IronWolf Pro: WD's Data Centre Drive Against Seagate's NAS Drive

Ultrastar vs IronWolf Pro: which IronWolf Pro are you comparing?

Start from the table, because the IronWolf Pro name covers two ratings. Seagate's newer IronWolf Pro sheet, DS2129.4-2311US, lists only NT models, with no NE models, and those sit level with every Ultrastar generation here on workload and warranty. Its 2022 sheet, DS1914.21-2206US, also lists an NE model at most sizes, rated for 300 TB a year with a lower MTBF. A listing that names the NE part number is the lower-rated drive, whatever the title says.

The Ultrastar side is simpler: the HC550 sheet gives workloads up to 550 TB a year, and the HC560, HC570 and HC580 sheets say the same with a 5-year limited warranty each. On ratings, then, an NT IronWolf Pro and an Ultrastar are interchangeable on paper, and the choice moves to the hardware rows.

IronWolf vs Ultrastar at 14TB to 22TB: cache, transfer and idle

Both makers print sustained transfer in MB/s and idle in watts, so these rows can be read across. On the IronWolf Pro side each row names the sheet revision, because the two revisions print different idle figures for the same 18 TB and 20 TB models.

Idle does not run one way. At 14 TB to 18 TB the IronWolf Pro prints lower figures than the HC550, 5.0 W or 5.2 W against 5.6 W. At 20 TB it depends on the revision and the variant: Seagate's newer 5.7 W for ST20000NT001 is 0.1 W under the HC560 BLE and 0.4 W under the ALE. At 22 TB the order flips, with ST22000NT001 at 6.0 W and the HC570 at 5.7 W. The two makers footnote their idle rows separately, so treat tenths of a watt as indications.

Transfer is closer than cache. The Ultrastar has twice the IronWolf Pro's cache at 14 TB to 20 TB, while at 22 TB Seagate's newer sheet gives ST22000NT001 512 MB. Sustained rates sit within a few MB/s of each other at most sizes, with the IronWolf Pro ahead at 18 TB, 285 MB/s against 269, and the HC560 ahead at 20 TB, 291 against 285. The NE models trail their NT001 siblings at 14 TB to 18 TB, with ST18000NE000 at 260 MB/s.

Ultrastar vs IronWolf Pro noise: both in bels, not the same test

This is one of the few NAS-against-enterprise pairs where both makers use the same unit. Seagate's IronWolf Pro SATA manual covers the 24, 20, 16 and 12 TB NT models and gives all of them 2.8 bels typical idle and 3.2 bels typical performance seek, which it calls A-weighted sound power. WD's Ultrastar sheets also use bels, labelled typical, as an idle and operating pair.

A shared unit is not a shared test. Seagate's active figure is labelled performance seek and defined as A-weighted sound power; WD's is labelled operating, and we have not found a WD document that names the load or the method behind it. For that reason the Seagate and WD rows above stay side by side without being set against each other, at idle or active.

Seagate's own two documents differ too. The IronWolf Pro data sheet prints 20 dBA idle and 26 dBA seek at 20 TB and 18 TB, while the manual prints bels, and we have not found a document that converts between them. The manual's model list runs 24, 20, 16 and 12 TB, so for an 18 TB IronWolf Pro the only noise figure is the data sheet's dBA.

We do not rank these drives on noise. Both makers use bels, but not the same test, and at 18 TB the IronWolf Pro has no figure in bels in any Seagate document we have found.

Ultrastar vs IronWolf Pro prices on Amazon.co.uk

With the NT ratings level against Ultrastar, the price per TB at your size is a fair tie-breaker. These are new listings on Amazon.co.uk, pounds sterling inc VAT; a dash marks a size where that line is not in stock right now.

In the IronWolf Pro list, NT and NE models sit together, so the last characters of the part number tell you which rating you are pricing. The Ultrastar list is drawn without HC555 or SS530 titles and carries SATA and SAS drives side by side. Both makers' sheets state CMR for the lines here, but the Recording column fills in only where a document names the exact part number.

Ultrastar or IronWolf Pro for a NAS

• Want the 550 TB/year rating from Seagate: pick an NT IronWolf Pro; the NE models on the 2022 sheet are rated 300.
• Want the larger cache at 14 TB to 20 TB: Ultrastar, at 512 MB against 256 MB.
• Want the lowest printed idle at 14 TB to 18 TB: IronWolf Pro. At 22 TB the HC570 prints the lower figure.
• Need 22 TB: both lines have a model, ST22000NT001 on Seagate's newer sheet and the HC570 on WD's.

Whether a NAS lists either drive is a question for its maker's compatibility list. For the WD side in more depth, the generation pages are HC550, HC560 and HC570, and the family is on WD Ultrastar. Seagate's own enterprise line against the IronWolf Pro is set out on Exos vs IronWolf Pro.