WD Ultrastar SAS: Model Numbers by Generation, and What SAS Changes

WD Ultrastar SAS prices on Amazon.co.uk

This table holds 20 listings right now. Lowest price per TB: £20.50/TB, pounds sterling inc VAT. The table includes HGST-branded Ultrastar listings, because the Ultrastar line is WD's, and it mixes new and used drives, so read the condition on each row before comparing prices.

The table follows the interface given for each listing. Some Ultrastar listings name no interface at all, and those cannot appear here even if they are SAS drives, so if you know the model number you want, check the model number tables below and search for it directly.

WD Ultrastar SAS model numbers, generation by generation

Each WD sheet prints the SATA and SAS models side by side. These are model numbers or patterns from each sheet, where x, y and z stand for characters WD varies by capacity, sector format or option. A cell marked "including" shows some of the sheet's models, not all of them:

The HC580 sheet lists its SAS models as WUH722424AL5201 and WUH722424AL5204 at 24 TB, and WUH722422AL5201 and WUH722422AL5204 at 22 TB. The HC520 is the 12 TB generation, with its power and sector figures further down. On the HC550, AL5200 appears only at 18 TB, which makes ten SAS model numbers on that sheet.

WD prints a key to these strings. The HC510 key defines 52 as 512e SAS 12Gb/s, 42 as 4Kn SAS 12Gb/s, E6 as 512e SATA 6Gb/s and N6 as 4Kn SATA 6Gb/s. The HC310 key adds A6 for 512n SATA and S2 for 512n SAS. The HC590 key uses the same E6 and 52 codes and gives the position after them as the Power Disable Pin 3 status: 0 for Power Disable support, L for the legacy Pin 3 configuration. So AL52 in a model number is a quick sign of a 512e SAS drive, from the HC310 to the HC590. The HC570's short 0F part numbers carry no such code, so match those to the sheet as whole numbers.

WD Ultrastar SAS vs SATA: idle power

On every WD sheet here, the SAS version idles higher than its SATA twin. By our subtraction the gap is largest on the HC310 and HC520, at 1.1 W each, then the HC320 at 1.0 W, and smallest on the HC550 at 0.2 W. On the three newest sheets, HC570, HC580 and HC590, it is 0.3 W. A full chassis of SAS drives adds that per bay, but for a handful of drives the choice of interface should come from your controller, not from the power figure.

The HC320 is the hungriest of these at idle in either interface, at 7.4 W SATA and 8.4 W SAS. The HC510, which also comes in 8 TB, is stated at 5.0 W and 5.8 W. If you are choosing between an 8 TB HC320 and an 8 TB HC510 for an always-on server, the HC510's sheet is the lower-power one by 2.4 W on SATA and 2.6 W on SAS, which is our subtraction.

Sector formats and speed: older SAS Ultrastars keep 520 and 528

• HC310 SAS: 512n and 512e at 512, 520 or 528 bytes, and 4Kn at 4096, 4104, 4160 or 4224. A 512n option is offered on the 4 TB model.
• HC320 SAS: 512e at 512, 520 or 528 bytes; the SATA model lists 512 only.
• HC510 SAS: 512e at 512, 520 or 528 bytes, against 512 on SATA, and 4Kn (AL42) as well as 512e (AL52) model patterns.
• HC520 SAS: 512e at 512, 520 or 528, and 4Kn at 4096, 4112, 4160 or 4224; the SATA models list 512 and 4096.
• HC550 SAS: the same 520 and 528-byte 512e formats, which the SATA models omit.
• HC570, HC580 and HC590: SAS and SATA alike list 512e at 512 bytes and 4Kn at 4096.

That is a real generation split. If your array documentation asks for 520 or 528-byte sectors, the newer HC570, HC580 and HC590 sheets do not list them for SAS, while the older generations do. We have not found a standards document that we can cite here, so we do not explain what those formats are used for.

On speed, the HC590 at 24 TB gives an interface transfer rate of 600 MB/s on SATA and 1200 MB/s on SAS, but the same sustained transfer rate, 287 MB/s (274 MiB/s), on both; at 26 TB the sustained figure is 302 MB/s on both. The SAS link is twice as wide, but the drive does not sustain more through it. Choose SAS because your server or array is SAS.

Will a WD Ultrastar SAS drive work in my server?

Only if the controller behind the bay is SAS. Seagate's knowledge base puts the rule plainly: "SAS drives cannot be plugged into SATA controllers." That holds for an Ultrastar as for any other SAS drive, so check the controller in your home server, NAS or workstation before you order. SAS vs SATA covers the rule in the other direction.

We have not found a port row on the WD Ultrastar sheets used here. If dual-path connection matters to your setup, ask WD or the seller about the exact model before you buy.

WD Ultrastar 4TB, 8TB, 10TB, 12TB and 22TB SAS: which generation

• 4 TB and 6 TB SAS: HC310, pattern HUS726TxTAL52yz, or S2 in place of 52 for 512n.
• 8 TB SAS: HC320 (HUS728T8TAL5201, 5204 or 5205) or HC510 at 8 TB.
• 10 TB SAS: HC510, pattern HUH7210xxAL520y for 512e or HUH7210xxAL420y for 4Kn.
• 12 TB SAS: HC520.
• 14 TB SAS: HC530, with models including WUH721414AL5201, 5204 and 5205, or HC550 (WUH721814AL5201, 5204, 5205).
• 16 TB and 18 TB SAS: HC550.
• 22 TB SAS: HC570 (WUH722222AL5201, WUH722222AL5204; WD part numbers 0F48051 SED and 0F48052 Base SE) or HC580 (WUH722422AL5201, WUH722422AL5204).
• 24 TB SAS: HC580 (WUH722424AL5201, WUH722424AL5204) or HC590.

At 16, 20, 22 and 24 TB the choice widens beyond WD, and our capacity pages compare Ultrastar SAS with Seagate and Toshiba at each size: 16TB SAS drives, 20TB SAS drives, 22TB SAS drives and 24TB SAS drives. For the HC550 in both interfaces, see Ultrastar DC HC550, and for the whole family WD Ultrastar.

Buying Ultrastar SAS drives for a business server

If you are buying SAS drives for a company's servers, the Consumer Rights Act 2015 may not be on your side. The Act's definition of a consumer is an individual acting for purposes wholly or mainly outside that individual's trade, business, craft or profession, so a firm stocking its own racks falls outside it.

If you are a private buyer purchasing from a trader, the Act does apply, and the short-term right to reject faulty goods ends after 30 days. Test a used SAS drive inside that window rather than leaving it on a shelf. For used SAS drives across makers, see refurbished SAS drives, and for refurbished Ultrastars in both interfaces, refurbished WD Ultrastar.