Seagate Exos SAS: Standard Part Numbers by Generation, and What SAS Changes

Seagate Exos SAS hdd prices on Amazon.co.uk

This table holds 8 listings right now. Lowest price per TB: £35.75/TB. Every price is pounds sterling inc VAT, and the button on each row reads Buy on Amazon. The table holds 3.5-inch Exos drives listed as SAS. The 2.5-inch 10K and 15K Exos models are a different class of drive, with far smaller capacities, and they are left out here.

A listing's title is the seller's description, and the part number is the safer test of the interface. Match the number on the listing against the SAS columns further down this page before you buy, and treat any listing that names no part number with caution.

Seagate Exos SAS vs SATA part numbers, X14 to X22

Each Exos X data sheet from the X14 to the X22 prints SATA columns beside SAS ones, so the SAS version of a capacity sits one cell across from its SATA twin. These are the standard FastFormat models, 512e/4Kn, as each sheet prints them:

In these tables every X22 number ends in E, every X20 number in D, every X18 number in J and every X16 number in G, while the X24 numbers end in H. The digits before that letter are what separate SATA from SAS, and they collide across generations. ST18000NM000D is the 18 TB X20 in SAS, but ST18000NM000J is the 18 TB X18 in SATA. ST20000NM007D is the X20 in SATA, but ST20000NM007H is the X24 in SAS. Reading only the capacity and the first few characters can put the wrong drive in your basket, so check the full number, last letter included.

The X14 breaks the pattern: its numbers end in four digits rather than a letter. Its SAS models are ST14000NM0048, ST12000NM0038 and ST10000NM0528, and the sheet lists its SAS columns as dual port against single port for SATA. These are the standard models only; each sheet also prints self-encrypting versions under other numbers.

Seagate Exos SAS numbers for the X24 and X10

The X24 SAS table is headed SAS 12Gb/s and offers three versions at each capacity, and it is the only sheet here where SAS reaches 24 TB:

• Exos X24 standard (Seagate Instant Secure Erase): ST24000NM007H at 24 TB, ST20000NM007H at 20 TB, ST16000NM007H at 16 TB and ST12000NM007H at 12 TB.
• Exos X24 SED: ST24000NM005H, ST20000NM005H, ST16000NM005H and ST12000NM005H.
• Exos X24 SED-FIPS: ST24000NM006H, ST20000NM006H, ST16000NM006H and, at 12 TB, ST12000NM009H. The X24 SATA table prints a dash in every SED-FIPS cell.
• Exos X10, 12 Gb/s SAS Standard table: ST10000NM0096 at 10 TB and ST8000NM0156 at 8 TB in 512e, plus ST10000NM0206 in 4Kn at 10 TB. The 8 TB 4Kn cell is a dash. Its SAS SED-FIPS 512e model is ST10000NM0236.

Exos 7E10 and 7E8 SAS: 2TB to 10TB in every sector format

The small Exos SAS capacities sit on the 7E10 and 7E8 sheets, and both give every sector format its own number. The 7E10 standard SAS models:

• 7E10 512n SAS: ST6000NM001B at 6 TB, ST4000NM001B at 4 TB and ST2000NM001B at 2 TB.
• 7E10 512e/4KN SAS: ST10000NM018B, ST8000NM018B, ST6000NM020B, ST4000NM025B and ST2000NM018B, from 10 TB down to 2 TB.
• 7E10 4Kn SAS: ST10000NM003B, ST8000NM003B, ST6000NM005B, ST4000NM005B and ST2000NM005B, from 10 TB down to 2 TB.
• 7E10 512e/4KN SED-FIPS 140-3 SAS: ST10000NM022B, ST8000NM022B, ST6000NM024B and ST4000NM029B.

The 7E8 SAS base models, which end in a digit rather than B:

• 7E8 512n SAS: ST6000NM0245 at 6 TB, ST4000NM0025 at 4 TB, ST3000NM0025 at 3 TB, ST2000NM0045 at 2 TB and ST1000NM0045 at 1 TB.
• 7E8 512e SAS: ST8000NM0075 at 8 TB, ST6000NM0095 at 6 TB, ST4000NM0125 at 4 TB and ST2000NM0135 at 2 TB.
• 7E8 4Kn SAS: ST8000NM0065 at 8 TB, ST6000NM0105 at 6 TB and ST4000NM0095 at 4 TB, plus ST2000NM0115, whose capacity cell on the sheet reads 0 rather than a size.

Some listings call the 7E8 512n SAS drives by an older Enterprise Capacity name. ST4000NM0025 and ST2000NM0045 are on the 7E8 sheet all the same, so a listing carrying either number can be checked against it. Every SAS model on the 7E10 tables is dual port, with interface access speeds of 12.0, 6.0 and 3.0 Gb/s, and the 7E8 SAS models are dual port too. For every 7E10 number, including the SED and other SED-FIPS models, see Exos 7E10.

Seagate Exos SAS vs SATA: idle power on the sheets

On most lines the SAS model idles a little higher. By our subtraction from Seagate's figures, the gap is 1.0 W at 10 TB and 0.5 W at 8 TB on the X10, 0.9 W at 8 TB on the 7E8, 0.4 W on the X20, 0.3 W at 18 TB and 0.4 W at 16 TB on the X18, 0.34 W at 10 TB and 0.18 W at 8 TB on the 7E10, and 0.2 W on the X24. The X16 prints 5.0 W for both interfaces. The X22 at 22 TB runs the other way, with SAS 0.24 W below SATA, although at 20 TB the same sheet puts SAS 0.1 W above.

Over a year the idle gap is small in energy terms. Take the X20, at 5.4 W in SATA and 5.8 W in SAS: a 0.4 W difference around the clock comes to about 3.5 kWh across 8,760 hours, which is our arithmetic rather than a Seagate figure. It adds up across a full chassis, but for a single drive it should not decide between SAS and SATA. The controller in your server should.

Under load the X24 gap widens. Seagate states 9.8 W random read and 8.2 W random write for X24 SAS on its 4K/16Q test, against 8.9 W and 7.1 W for X24 SATA, so 0.9 W and 1.1 W more on the SAS side by our subtraction.

What SAS changes on a Seagate Exos sheet

• Ports: Dual in the SAS columns and Single in the SATA columns of the X24, X22, X20, X18, X16 and X14 sheets. The 7E10 and 7E8 SAS tables are dual port throughout.
• Interface: each X-series SAS table from the X10 to the X24 is headed 12Gb/s; the X16 and 7E10 SAS rows read 12.0, 6.0 and 3.0 Gb/s, where the X16 SATA rows read 6.0 and 3.0 Gb/s.
• Sector sizes: 512, 520 and 528 bytes on the SAS tables of the X24, X22, X20, X18 and X10, and on the 7E10 512e/4KN SAS table; the SATA columns print 512. Among the 512-byte formats, the exception is the 7E10 512n SAS table, which prints 512 only.
• Protection information: T10 DIF reads Yes on the SAS tables of the X22, X20, X18, X16, X14, X10 and 7E8, and the X22 and X10 SATA columns print a dash.
• Security: from the X14 to the X24, SED-FIPS models appear only in the SAS columns. The X10, 7E8 and 7E10 sheets list SATA SED-FIPS models too.
• Sustained transfer: the X20 states 285 MB/s for SAS and SATA alike. The exception is the 7E10 512n tables, at 236MB/s for SAS against 215MB/s for SATA.

The SED-FIPS models make the security point concrete. The X20 lists ST20000NM005D and ST18000NM002D, the X16 ST16000NM009G and ST14000NM012G, and the X14 ST14000NM0378 and ST12000NM0368, each in a SAS column with a dash beside it in SATA. On the X10, by contrast, ST10000NM0176 and ST10000NM0186 are SATA SED-FIPS models; the 7E8 lists SATA SED-FIPS numbers such as ST8000NM0155, and the 7E10 lists ST10000NM021B in SATA beside ST10000NM022B in SAS.

We have not found a T10 or SNIA document that we can cite, so we do not explain what 520 and 528-byte sectors or T10 DIF do beyond the sheets' own wording. If your array or controller documentation asks for either, check that the SAS table for your Exos line prints it before you order. Which controllers accept which drives is covered on SAS vs SATA; read it before you put a SAS drive in a bay whose controller you have not checked.

Seagate Exos SAS 2TB, 4TB, 8TB, 16TB, 20TB and 24TB: the numbers to look for

• 2 TB: ST2000NM001B, ST2000NM018B or ST2000NM005B (7E10), and ST2000NM0045 or ST2000NM0135 (7E8).
• 4 TB: ST4000NM001B, ST4000NM025B or ST4000NM005B (7E10), and ST4000NM0025, ST4000NM0125 or ST4000NM0095 (7E8).
• 8 TB: ST8000NM018B or ST8000NM003B (7E10), ST8000NM0075 or ST8000NM0065 (7E8), and ST8000NM0156 (X10, 512e).
• 16 TB: ST16000NM007H (X24), ST16000NM004J (X18) and ST16000NM002G (X16).
• 20 TB: ST20000NM007H (X24), ST20000NM000E (X22) and ST20000NM002D (X20).
• 24 TB: ST24000NM007H (X24), with SED and SED-FIPS versions ST24000NM005H and ST24000NM006H.

At 16, 20 and 24 TB the choice widens beyond Seagate. 16TB SAS drives, 20TB SAS drives and 24TB SAS drives compare Seagate with Western Digital and Toshiba at each size, with their own live tables, so this page keeps to the Seagate ladder.

At 8 TB three different Exos SAS lines overlap, and they are not interchangeable on paper. The X10 SAS model idles at 5.5 W, the 7E10 at 7.24 W and the 7E8 at 8.5 W. The X10 SAS table offers both 512e and 4Kn at 10 TB but only 512e at 8 TB. If you are replacing a failed drive in an array, the safest match is the same part number.

Exos M and recertified Exos: no SAS table we have found

The Exos M data sheet carries one specification table, headed SATA 6Gb/s, with single-port models at 24, 28, 30 and 32 TB. We have not found a Seagate document that lists an Exos M in SAS, so for SAS above 24 TB this page has no Seagate number to give you.

Seagate's factory recertified data sheet, DS39.1, lists SATA models only, with numbers ending in C from 4 TB to 32 TB. A used, renewed or refurbished Exos SAS listing on Amazon.co.uk therefore matches no number on that sheet, so treat it as the seller's own description of a used drive. The condition column shows new or used, and the tables below split them.

Across the new and used tables: 8 listings in new condition and 2 listings in used condition. For used SAS drives across every maker, and what to check on a listing before you buy one, see refurbished SAS drives. For the SATA side of the same family, see Seagate Exos SATA.