12TB Enterprise HDD: Four Exos Lines, Ultrastar HC520, Toshiba and WD Gold

12TB enterprise SATA HDD and SAS HDD part numbers

Four Exos lines, two Toshiba series and two WD lines all reach 12 TB on the sheets we read. The strings below are the way to tell them apart.

Watch the last letter. ST12000NM002G is the Exos X16 on SAS, ST12000NM002H is the Exos X24 on SATA, and ST12000NM002C is on Seagate's factory-recertified sheet. Only one character separates them, yet the sheets treat them as three different products on different interfaces or programmes. A title that gets the ending wrong may be describing another drive, so read it carefully. We do not decode the letters.

12TB enterprise HDD price on Amazon.co.uk

At the last price check, the table held 17 listings for enterprise-class drives in stock. Lowest price per TB at the last check: £26.02/TB. All of these are pounds sterling inc VAT.

Our Recording column leans on maker documents for the exact part number. Where it says not sourced, treat any CMR wording in the Amazon title as a seller's description.

Enterprise hard drive 12TB from Seagate: X14, X16, X18 and X24

Twelve terabytes is a lower rung on each of these Exos ranges rather than the headline size.

• Exos X14: its 12 TB models have a 245 MB/s maximum sustained rate at the outer diameter, against 261 MB/s for its 14 TB models, and state 5 W idling average on SATA and SAS.
• Exos X16: 5.0 W idle and 670 g.
• Exos X18: the 12 TB SATA drive is stated at 4.4 W Idle A average, and the 12 TB SAS drive at 5.0 W. Both weigh 650 g.
• Exos X24: 12 TB sits in a standard-model row beside 24 TB, 20 TB and 16 TB, with a 512MB multisegmented cache. The sheet prints 6.3 W on SATA and 6.5 W on SAS at every one of those capacities, so the 12 TB drive idles like its 24 TB sibling.

We did not find an Exos X12 document, so we say nothing about that line. Family comparisons across every capacity live on the Seagate Exos page; this page stays at one size.

Ultrastar DC HC520: eight disks in a 12 TB drive

WD describes the HC520 as the industry's first 12 TB drive. Its fourth-generation HelioSeal technology enables an eight-disk design, which WD says increases capacity by 20% over the seven-disk HC510 before it. Stated idle power is 5.0 W for SATA and 6.1 W for SAS, and maximum weight is 660 g.

The sheet's key reads the four model forms. E6 is 512e SATA, N6 is 4Kn SATA, 52 is 512e SAS and 42 is 4Kn SAS. The trailing y is the data security mode, so the middle characters tell you the interface and format, and the last one varies. HUH721212 is the shape of string to look for in a title.

Toshiba at 12 TB: MG07ACA and MG09

Toshiba's MG07ACA overview describes what it calls the world's first nine-disk helium-sealed design, and states 4.25 W typical active idle at 12 TB against 4.53 W at 14 TB. Its label is a typical value, so it is not strictly like for like with an average. The overview describes a SATA drive, so the series has no SAS part to look for.

The MG09 overview lists MG09ACA12TE as SATA-3.3, 12 TB, 512e, and MG09SCA12TE as its SAS-3.0 counterpart, and describes a nine-disk helium-sealed design for the series. The wider series is covered on our Toshiba MG series page.

Idle power and noise: where the air-filled WD Gold stands out

WD's own Gold table is the telling one. Its drive technology row marks the 16 TB and 14 TB models as helium and the 12 TB as air. The 12 TB idles at 8.4 W against 5.6 W for those larger drives, and at 34 dBA against 20 dBA in idle mode. So the 12 TB Gold is both hungrier and louder at idle than a Gold with more capacity. If the drive will sit near people, that matters as much as the watts.

That 2.8 W gap comes to about 24.5 kWh a year per drive if it idles for all 8,760 hours. The figure is our working, not WD's, and it leaves load out.

12TB enterprise SAS HDD listings

The penalty for SAS at 12 TB runs from nothing to over a watt: the X14 and X16 state the same idle on both interfaces, the X24 adds 0.2 W, the X18 0.6 W and the HC520 1.1 W. This list narrows the first table to rows we can read as SAS, so it can be short. Settle what your backplane or controller takes before you shop by price. The SAS hard drives page looks at the interface across sizes.

New 12 TB listings, and what recertified means on Seagate's sheet

Seagate's factory-recertified sheet carries ST12000NM002C, ST12000NM003C and ST12000NM004C at this capacity, with a 6-month limited warranty and a 190 MB/s maximum sustained rate. The four Exos sheets print 245 MB/s to 285 MB/s at 12 TB, so the recertified figure is lower than any of them. A used condition on Amazon.co.uk does not by itself make a unit one of these, and the sheet does not tie those numbers to a named Exos line, so neither do we. If you buy as a consumer from a trader, your statutory rights sit apart from that maker warranty. See refurbished enterprise hard drives for the wider question.