WD Ultrastar vs WD Gold: Two Western Digital Enterprise Lines Compared at 18TB to 26TB

Ultrastar vs WD Gold: ratings that do not separate them

Both lines come from Western Digital, and on paper WD rates them for the same job. The Gold sheet covers read-write workloads of up to 550TB per year, a 5-year limited warranty and 2,500,000 hours projected MTBF at every capacity from 18 TB to 26 TB. Each Ultrastar sheet from the HC550 to the HC590 gives workloads up to 550 TB a year and a 5-year limited warranty as well.

With the ratings level, the choice between a Gold and an Ultrastar of the same size comes down to the few per-capacity rows where WD prints different numbers, and to price. WD's own sheets add that MTBF and AFR figures neither predict how long a particular drive lasts nor form a warranty, which is one more reason not to choose on that row.

WD Gold vs Ultrastar at 18TB, 20TB, 22TB, 24TB and 26TB

Here the two lines can be read directly against each other, because both WD sheets print maximum sustained rate in MB/s and idle power in watts. Each sheet footnotes its own idle row.

Two sizes line up exactly. At 18 TB the Gold and the HC550 both print 269 MB/s and 5.6 W. At 22 TB the Gold and the HC570 both print 291 MB/s and 5.7 W. We have not found a WD document saying the drives share hardware, so the match is noted and nothing more is drawn from it.

At 20 TB the Gold idles lower than either HC560 variant, 5.3 W against 5.8 W or 6.1 W, with a sustained figure 6 MB/s below. At 24 TB and 26 TB the Ultrastar figures run ahead on sustained rate, 298 and 287 MB/s at 24 TB and 302 MB/s at 26 TB against the Gold's 279 and 285, while idle sits within 0.1 W. We have not found where on the platter the Gold sheet measures its sustained rate, so a gap of a few MB/s is an indication rather than a measured difference.

WD Gold vs Ultrastar: ArmorCache at 22TB and above

ArmorCache is one of the few features WD lists by capacity, and it follows the same line in both families. The Gold sheet marks it Yes on the 26 TB, 24 TB and 22 TB models and No on the 20 TB and 18 TB. On the Ultrastar side, the HC570 and HC580 sheets list it as Supported, and the HC590 sheet describes two modes: write cache disabled for increased random write performance, or write cache enabled to protect cached data in case of an emergency power off or unexpected power loss.

So from 22 TB up, both lines list ArmorCache on WD's sheets. If you want it, the 18 TB and 20 TB Gold models are the ones to skip.

Ultrastar vs Gold noise: dBA on one WD sheet, bels on the other

WD uses two different conventions in these two families. The Gold sheet reports average acoustics in dBA, for idle mode and for seek mode. The Ultrastar sheets give a typical pair in bels, idle against operating. We have not found a WD document that explains either method or converts between them, so the two lines cannot be ranked on noise even though one company wrote both sheets.

Each family moves at the same sizes, which is as far as the numbers go. Gold's idle figure steps up from 20 dBA to 25 dBA on its 24 TB and 26 TB models, and Ultrastar's from 2.0 to 2.5 bels on the HC590, the generation that covers those two sizes. That 2.5 comes from an HC590 line WD prints as Operating/Idle, 3.2/2.5, reversing the earlier order; it is read here as labelled. At 18 TB both families also print their largest active figure: 36 dBA seek on the Gold, 3.6 bels operating on the HC550.

We do not rank Gold against Ultrastar on noise. Gold's figures are averages in dBA, Ultrastar's are typical values in bels, and Gold's seek mode is not stated to be the same test as Ultrastar's operating figure.

Ultrastar vs Gold recording technology

Every Ultrastar generation in the tables states CMR on its own sheet: the HC550, HC560, HC570, HC580 and HC590. We have not found a recording technology on WD's Gold data sheet. In the price tables below, the Recording column shows a technology only where a document ties it to the part number, so Gold rows may show none.

Ultrastar vs WD Gold prices on Amazon.co.uk

Since the sheets put the two lines so close, price per TB at a given size often settles it. The block below gives the lowest new figure on Amazon.co.uk for each line at each size, pounds sterling inc VAT; a dash means no in-stock row at that size for that line right now.

Gold rows with WDS in the title are kept out, since those are WD's Gold-branded SSDs rather than hard drives. On the Ultrastar side, titles naming the HC555 or SS530 are kept out, SATA and SAS share one list, and many listings carry only a part number, so use the size-by-size map near the top to place each one.

Choosing between WD Gold and Ultrastar

• At 18 TB or 22 TB the sheets give Gold and the matching Ultrastar the same sustained rate and idle power, so price and stock decide.
• At 20 TB the Gold prints the lowest idle in the tables, 5.3 W, but no ArmorCache.
• At 24 TB and 26 TB the Ultrastar sheets print the higher sustained rates, and both lines list ArmorCache.
• Ratings are level throughout: 550 TB a year and 5 years on every sheet here.

For more on either family, WD's Gold range has a UK page at WD Gold, and each Ultrastar generation has its own: HC550, HC560, HC570, HC580 and HC590, all under WD Ultrastar.