Seagate Exos: X20, X22 and X24 Compared, With Amazon.co.uk Prices

Seagate Exos prices on Amazon.co.uk: new drives

This table lists 37 in-stock new Exos offers on Amazon.co.uk, sorted by pounds per TB inc VAT. The lowest figure is £23.04/TB, on the Seagate Exos 26TB Internal Hard Drive at £599.00. The lowest outlay among these rows is £105.92, which can be a much smaller drive, so look at the capacity column before comparing the two numbers.

Start with the part number column. The filter behind this table is wider than the three generations compared below: it can also return 2.5 inch SAS and 7E-series Exos rows, so check each part number. We have not opened data sheets for those, nor for X16, X18 or X28, so the specifications on this page do not describe them. The Recording column prints a technology only where a document supports it. The letters CMR in an Amazon title are a seller's claim, not evidence.

Exos X24 vs X20: what the data sheets change

Seagate's sheets for X20 and X24 agree on one thing the generation names might hide. Both state the same maximum sustained rate on their SATA models, 285 MB/s at the outer diameter, and so does X22. The differences a buyer can act on are capacity points, part numbers, cache and idle power.

Exos X22 sits between them at 22 TB and 20 TB. Its SATA models are ST22000NM001E and ST20000NM004E, and its SAS models are ST22000NM000E and ST20000NM000E. The cache is 512 MB, the same as X24 and double the 256 MB on X20. Average Idle A power is 5.74 W at 22 TB SATA, 5.4 W at 20 TB SATA and 5.5 W on both SAS models.

Newer did not mean lower idle power on these sheets. At 20 TB on SATA, X20 and X22 both list 5.4 W and X24 lists 6.3 W. That 0.9 W gap comes to about 7.9 kWh over the 8,760 power-on hours Seagate counts in a year. This is our arithmetic from the sheets, at idle only, and not a measured running cost.

Seagate Exos 20TB: X20, X22 or X24, SATA or SAS

Seagate Exos 20TB is a search that can land on any of three generations, because all three list the capacity. Six standard part numbers cover the same headline size:

• Exos X20: ST20000NM007D on SATA, ST20000NM002D on SAS.
• Exos X22: ST20000NM004E on SATA, ST20000NM000E on SAS.
• Exos X24: ST20000NM002H on SATA, ST20000NM007H on SAS.

The digits do not carry across generations. In these rows 007 is SATA on X20 and SAS on X24, while 002 is SAS on X20 and SATA on X24. The final letter changes too: D, E and H. We have not found a Seagate document that defines these segments, so we print the observed list and no decode. Search for the whole number, not for a pattern.

The table below holds 2 Exos 20 TB rows, new and used together, with the lowest at £31.77/TB. This page stays with Exos; the wider 20 TB hard drive choice spans other makers.

Seagate Exos 24TB: two lines share the capacity

Seagate Exos 24TB is where the exact part number saves the most trouble. The X24 sheet lists ST24000NM002H on SATA and ST24000NM007H on SAS. Seagate's Exos portfolio sheet, DS2046.1-2512, also lists ST24000NM001K on SATA 6 Gb/s, in a separate line alongside 32 TB, 30 TB and 28 TB models. Their figures are not the same.

Sharing a table with a 32 TB drive does not make the 24 TB model as quick: the 32 TB model in that line states 285 MB/s against 240 MB/s. Watch one more near miss. ST24000NM001H is the self-encrypting X24 SATA model, one character away from ST24000NM001K.

The table holds 2 Exos 24 TB rows, new and used together, and the Condition column matters here. Before setting £25.26/TB against any new offer, confirm which condition that row is. For other makers at this size, the choice belongs to the broader 24 TB hard drive question.

Exos X24 datasheet: models, sectors and ports

These are the X24-family models by option at 24 TB, 20 TB, 16 TB and 12 TB, in that order. The 12 TB SED-FIPS number breaks the pattern, so do not guess it from its neighbours.

• SATA, single port, 6.3 W average Idle A: ST24000NM002H, ST20000NM002H, ST16000NM002H, ST12000NM002H.
• SAS, dual port, 6.5 W average Idle A: ST24000NM007H, ST20000NM007H, ST16000NM007H, ST12000NM007H.
• SED SATA: ST24000NM001H, ST20000NM001H, ST16000NM001H, ST12000NM001H.
• SED SAS: ST24000NM005H, ST20000NM005H, ST16000NM005H, ST12000NM005H.
• SED-FIPS SAS: ST24000NM006H, ST20000NM006H, ST16000NM006H, ST12000NM009H.

Sector sizes differ by interface. SATA models list 512 bytes under 512e and 4,096 bytes under 4Kn. SAS models add 520 and 528 bytes under 512e, and 4,160 and 4,224 bytes under 4Kn. FastFormat models ship in 512e and can be switched to 4Kn, but the switch erases data, so make that decision before the drive holds anything.

Seagate rates these SATA and SAS models at 2,500,000 hours MTBF and 0.35% AFR at full 24x7 operation, with a 5-year limited warranty. Its X24 sheet marks every listed capacity as CMR and describes a helium-sealed drive. Those are the maker's ratings, not results we have measured.

No data sheet can tell you what your chassis accepts, so confirm the backplane and controller before choosing an interface. The wider SAS vs SATA decision sits outside this page.

Exos above and below X24: 32 TB down to 2 TB

Seagate says what was once split across X, E and M now sits under a single Exos name, which is one more reason to search by part number rather than by a line letter. Its portfolio sheet says the newest generation reaches up to 32 TB in a 3.5 inch form factor at 3 TB per platter. Its SATA models at 32 TB, 30 TB and 28 TB are ST32000NM004K, ST30000NM004K and ST28000NM003K, which with the 24 TB above are rated at 2,500,000 hours MTBF and 0.35% AFR with a 5-year limited warranty.

At the small end the same sheet lists 512e/4Kn models from 10 TB to 2 TB. On SATA they are ST10000NM017B, ST8000NM017B, ST6000NM019B, ST4000NM024B and ST2000NM017B. On SAS they are ST10000NM018B, ST8000NM018B, ST6000NM020B, ST4000NM025B and ST2000NM018B. Their ratings are lower on paper: 2,000,000 hours MTBF and 0.44% AFR, still with a 5-year limited warranty.

Seagate Exos refurbished: the used rows

If you searched for Exos refurbished or recertified, this is the nearest table we can offer: 19 Exos offers held as used on Amazon.co.uk, from £20.49/TB. The table says used and goes no further. The seller's own wording is on the Amazon.co.uk listing, so go by that.

We have not opened a Seagate document on recertified drives. So we state nothing about how such a unit is tested, or whether the 5-year limited warranty on the data sheets passes to it. Ask the seller, and ask Seagate with the serial number, before relying on it.

Two protections are easily confused. GOV.UK's guidance tells sellers they must offer a full refund if an item is faulty, not as described or does not do what it is supposed to. That duty sits with the seller. A manufacturer's warranty is a separate promise from the maker. The same split applies across refurbished enterprise hard drives generally.