24TB SAS Drive: Exos X24 Against Ultrastar HC590, and the 24TB Drives That Are Not SAS

24TB drives that are not SAS: what the sheets show

Several well-known 24 TB products sit on the SATA side of their makers' documents, and each looks like a natural pick until you read the header. Seagate says SATA drives may be plugged into SAS controllers, so one might still fit a SAS shelf, but buying one will not get you a SAS drive.

That last row leaves a used SAS listing with no recertified sheet to be checked against, and the terms of a SATA table should not be read across to it.

24TB SAS Seagate Exos X24 against WD Ultrastar HC590

Seagate's release of 18 October 2023 says the helium 3.5-inch, 7200 RPM nearline drive comes with both SATA and SAS. The portfolio sheet coded 2512, with a 2025 copyright, keeps ST24000NM007H in its SAS 12 Gb/s table, and Seagate's DS2080-2307US sheet labels that number Exos X24. WD's HC590 sheet lists a 24 TB SAS model under the form WUH722624ALxxyz, where 52 in the xx position means 512e SAS 12 Gb/s.

Two rows differ most clearly. WD's idles 0.6 W lower. Against the HC590, Seagate's offers the wider sector sizes, so if your system expects 520 or 528 byte sectors, the HC590 row as we read it does not list them. The operating figures are labelled differently on each sheet, so we would not call either drive the lower-power one under load.

The HC590 at this size has 1,100 Gbits per square inch of areal density, and its interface limit is 1,200 MB/s on SAS and 600 MB/s on SATA. WD rates it at 550 TB a year. Moving from its SATA to its SAS version costs 0.3 W on both of the power rows above. Both makers' sheets give a 5-year limited warranty. That is the maker's sheet, and it does not tell you what a particular seller's listing carries.

Other 24TB SAS models: HC580 and Toshiba MG11

The two drives above are the ones we compare row by row, not the only choices. WD's HC580 has 24 TB SAS models, WUH722424AL5201 and WUH722424AL5204, with 5.8 W idle and a printed 0.24 W/TB.

Toshiba's MG11SCA24TE has the lowest idle figure of the four: 4.83 W active idle, from a merged cell covering 24, 22 and 20 TB, which is 0.20 W/TB by our division. Toshiba's operating figure is 8.57 W write/read at 4KB Q1, a different test from either sheet above. The MG11 SAS table also lists 520 and 528 byte host sectors, so Seagate is not alone in offering them. The Toshiba MG series page sets out that family.

24TB SAS price on Amazon.co.uk

The table above holds 2 listings right now. Rows depend on the interface our catalogue records for each listing, so check that against the printed part number. Seagate's SAS 24 TB numbers are ST24000NM007H, ST24000NM005H and ST24000NM006H. Seagate prints ST24000NM002H in its SATA table, so a listing with that number is SATA on the sheet even if it appears here as SAS. Likewise, a WD row that prints no model number gives you no 52 code to read, so ask the seller for it.

A Synology HAS5320-24T is also catalogued with a SAS interface. We have no Synology document for it, so it stays out of our comparison. The 24TB hard drive page covers every interface at this size.

In-stock alternatives

None of these is the product this page covers: they are what is in stock on Amazon.co.uk beside it right now. Each row says why it is listed. Check the interface, form factor and part number against your system before buying.

Encryption options: 24TB SAS hdd part numbers and codes

The two makers identify encryption differently. Seagate gives each option its own part number. WD uses the last character of the model number, its z position.

A footnote on Seagate's sheet affects anyone buying an encrypted version. It says Self-Encrypting Drives and FIPS 140-3 Validated drives are available through franchised authorised distributors, and may require TCG-compliant host or controller support. Before choosing ST24000NM005H or ST24000NM006H, confirm that your controller handles it, and ask who the seller is in relation to that distribution route.

Fitting a 24TB SAS drive

Seagate's installation page tells you to make sure the drive makes firm contact with the host's SAS backpanel connector. A SATA-only controller is the blocker, and our 20TB SAS drive page holds the complete rule from Seagate's knowledge base. We read Seagate's line about SATA drives on SAS controllers as a statement about what can connect, not a promise about mixing both interfaces on one particular backplane, and the SAS vs SATA comparison goes wider. If you are weighing smaller drives, the 16TB SAS drive page sets out more lines than are compared here.