6TB Enterprise Hard Drive: Exos, Ultrastar and WD Gold Part Numbers Compared

6TB enterprise hard drive prices on Amazon.co.uk

This table holds 16 listings right now. Lowest price per TB: £22.50/TB, pounds sterling inc VAT. New and used drives share the table, and 6 TB spans several generations, so the part number on each row matters more than the brand. The sections below say which numbers belong to which sheet.

Some 6 TB listings carry numbers for which we have not found a maker's sheet: HGST Ultrastar 7K6000 numbers such as HUS726060ALE610 and HUS726060AL5210, the He6 HUS726060ALA640, the Seagate ST6000NM021A, and WD Gold WD6003FRYZ and WD6002FRYZ. The WD Gold sheet lists WD6005FRYZ and WD6004FRYZ instead. If a row shows one of those other numbers, the figures below do not describe it, and you should find the maker's sheet for that exact number before you buy.

6TB enterprise part numbers and idle power, sheet by sheet

The spread is wide. The lowest idle figure here, 5.9 W for the HC310 in SATA, is about 2.7 W below the highest, 8.57 W for the 7E8 512n SAS model, by our subtraction. Divided by 6, which is also our arithmetic, that is roughly 0.98 W/TB for the HC310 SATA, 1.04 W/TB for the 7E8 512e SATA, 1.08 W/TB for the Gold WD6005FRYZ and 1.18 W/TB for the 7E10 512e SATA. WD's Gold sheet prints 1.2 W/TB as WD6005FRYZ's own efficiency index, which does not match its 6.5 W idle figure divided by 6. WD states one HC310 idle figure for its 6 TB and 4 TB family, so the 6 TB value is shared, not separate.

Format changes the figure inside one family. On the 7E10 the 6 TB 4Kn SATA model is stated at 6.04 W, the 512n and 512e/4KN SATA models at 7.06 W. On the 7E8 the 512e SATA model idles at 6.26 W against 8.15 W for the 512n one. So two 6 TB Exos drives with the same badge can differ by nearly 2 W at idle, and the part number is the only way to tell which you are buying.

Speed, cache and noise at 6TB

• Exos 7E8: 215MB/s maximum sustainable transfer on the 512n SATA model and 226MB/s on the 512e SATA model, with a 256MB cache at 6 TB.
• Exos 7E10: 215MB/s on the 512n SATA model and 236MB/s on the 512n SAS model, with a 256MB cache.
• Ultrastar DC HC310: sustained transfer up to 255MB/s in 512e/4Kn; acoustics 2.9 bels idle and 3.6 bels operating, typical.
• WD Gold: 275MB/s for WD6005FRYZ and 267MB/s for WD6004FRYZ, both with a 256MB cache; 29 dBA idle and 36 dBA seek.

On paper the WD Gold WD6005FRYZ is the fastest 6 TB drive here and the 512n SATA Exos models the slowest, at 215MB/s. WD gives HC310 noise in bels and Gold noise in dBA. Those are different measures, so we print each in its own unit and do not rank one drive's noise against the other's.

CMR, MTBF and warranty on a 6TB enterprise drive

Seagate describes the 7E8 as built on field-proven 9th-generation conventional magnetic recording, and WD says the HC310's 6 TB and 4 TB capacity points use conventional magnetic recording (CMR) on an air-filled platform. For WD Gold, WD's en-GB product page states that "WD Gold drives use CMR (Conventional Magnetic Recording) technology", though we have not found a recording row on the Gold data sheet itself. We have not found a statement of recording technology for the 7E10, so this page does not call it CMR.

• MTBF: 2 million hours on the 7E8, 7E10 and HC310 sheets, and 2,000,000 hours projected on the Gold sheet.
• Annualised failure rate: 0.44% on the 7E8, 7E10 and HC310 sheets.
• Warranty: 5-year limited on the 7E8 and 7E10 sheets, 5 years on the HC310 sheet, and a 5-year limited warranty for WD6005FRYZ and WD6004FRYZ on the Gold sheet.

A maker's warranty on a sheet is not a promise about a particular listing, and a used drive's terms are whatever its seller states. Read the listing before you buy.

Recertified 6TB: Seagate's own numbers

Seagate's factory recertified sheet lists 6 TB as ST6000NM000C, ST6000NM001C and ST6000NM002C. It is a SATA 6 Gb/s CMR sheet, and its figures differ from the new drives above: a 6-month limited warranty, 190MB/s maximum sustained transfer and 7.2 W idle.

Two more rows are worth setting side by side. The new 7E8 sheet gives 8,760 power-on hours a year and one non-recoverable read error sector per 10E15 bits read. The recertified sheet labels its row Power-On Hours per Year (24x7) and prints 2,400, with one sector per 10E14 bits read. Choose a recertified drive with those figures in mind, rather than reading a new drive's sheet for it. For used and recertified drives across capacities, see refurbished enterprise hard drives.

6TB enterprise SAS drives and new-only listings

The SAS table holds 5 listings right now. The new-condition table holds 12 listings. Check your server's controller before you choose from the SAS table; SAS vs SATA explains which drives work where. The 6 TB SAS numbers on the sheets above are ST6000NM0245, ST6000NM0095 and ST6000NM0105 on the 7E8, and ST6000NM001B, ST6000NM020B and ST6000NM005B on the 7E10.

For the full 7E10 range at every size, see Exos 7E10. Either side of this capacity, 4TB enterprise hard drives and 8TB enterprise hard drives compare the same makers, and WD Gold covers the whole Gold line.