28TB Hard Drive: Exos M, the Limited Shingled X24 and Seagate's Recertified Numbers

What a 28TB hard drive is: Exos M on Mozaic 3+

Seagate's Exos M sheet lists ST28000NM003K as its 28 TB CMR model, in a line with 24, 30 and 32 TB. The sheet says the drive blends 90% of trusted, proven components from previous generations with Mozaic 3+ technology. The link to HAMR comes from Seagate's January 2025 release, which describes Exos M as based on Mozaic 3+ and calls Mozaic 3+ its heat-assisted magnetic recording platform.

The 28 TB position is the interesting one in that table. It gives up only 5 MB/s against the 30 TB model, but gains 30 MB/s over the 24 TB model at the bottom of the line. Power stays flat across the column: the sheet prints 6.9 W average idle and 9.5 W maximum at random read for each capacity. So moving up from 24 TB to 28 TB costs nothing on those two power rows.

For reliability, the sheet gives 2,500,000 hours MTBF, a 0.35% annualised failure rate and a 5-year limited warranty, with single-port SATA. The standard model row is labelled 512e. A footnote warns that switching from 512e to 4Kn with the FastFormat routine deletes all data on the drive, so choose the format before the drive holds anything.

Seagate's later sheet DS2045.4-2511 lists the same ST28000NM003K under the plain name Exos and says Mozaic without the 3+. Go by the part number rather than the name on the sheet.

28TB hard drive price on Amazon.co.uk

Every figure is pounds sterling inc VAT, sorted on price per terabyte. Our catalogue rejects external drives and multi-packs, so each row is a single internal drive. Top position only means the lowest figure per terabyte, so go by the part number and the Condition column rather than the order of the rows.

The second table narrows to rows whose listing names the Exos line, which is wider than Exos M. Compare each part number with ST28000NM003K. Where a row prints no part number, ask the seller first.

The other 28TB: a shingled Exos X24 configuration

Not every 28 TB Seagate is CMR. Seagate's October 2023 release says it continues to offer limited cloud customers a shingled magnetic recording Exos X24 configuration at a capacity of up to 28 TB. That is a separate product from the CMR Exos M, even though the capacity matches.

We have not found a part number for that shingled configuration, so we cannot give you one to avoid or to look for. The practical test is simpler. If a listing says Exos X24 and 28 TB, do not assume CMR on the strength of the capacity, and do not assume it is an Exos M either.

28TB hard drive refurbished: what Seagate's recertified sheet covers

This section describes a maker's document, not an offer. Seagate's Factory Recertified sheet has a 28 TB column with three part numbers: ST28000NM000C, ST28000NM001C and ST28000NM002C, under the heading SATA 6 Gb/s.

The recertified column also prints 7,200 RPM, and Seagate's support page lists ST28000NM000C with a 6-month limited warranty. Neither document says which earlier drive a recertified unit came from.

A used row does not prove any of this. Amazon's condition label and a matching part number do not by themselves show that a unit went through Seagate's own programme, so the six months may not be yours to claim. Ask the seller who recertified the drive and who stands behind it. Our page on refurbished enterprise hard drives goes further into that question.

28TB hard drive NAS use: IronWolf Pro or Exos

Seagate's July 2025 release names an IronWolf Pro 28TB beside the Exos M, and says both were available through Seagate's online store as well as its authorised resellers and channel partners worldwide. It places them on Mozaic3+ with HAMR. Beyond that we have not found a document giving an IronWolf Pro 28 TB part number, workload rate or warranty, so we state none of the three. Our table may show such a row, but its figures come from the listing.

Seagate's IronWolf Pro page describes the range as up to 32 TB with CMR, and the page text we read names no 28 TB model. So its family-level NAS testing statement, which the 30TB hard drive page quotes, does not settle whether a given machine accepts this size. Check the drive's part number against your NAS maker's own list.

The Exos sheet points in a particular direction: DS2045.4-2511 gives NAS systems exceeding 16 drive bays as a best-fit application. We have not found a Seagate statement about smaller units on that sheet, so read it as where Seagate aims the drive rather than a ban on anything smaller. The 24TB hard drive page gives the size below.