SAS vs NVMe: What Each Connects To, How Fast It Is and What Amazon.co.uk Lists

SAS hard drive vs NVMe SSD: what the Amazon.co.uk tables show

Start with the listings, because they reshape the question. The SAS table holds 95 hard drive rows at this refresh, every form factor and class included, with Western Digital WD WUH721818AL5204 18TB SAS 7.2K RPM 512M 0F38353 512e/4Kn S... (used) lowest at £20.50/TB. The NVMe table holds 20 enterprise SSD rows, with Intel 4TB SSD DC P4510 2.5 U.2 NVMe PCIe SSDPE2KX040T8 SSDPE2KX040T801 Solid... (used) lowest at £185.00/TB. A third query looks for SAS SSDs and returns 0 rows, and we keep that one out of the tables.

The SAS table on this page contains hard drives only. SAS SSDs exist, and maker figures for them appear below, but they enter a price comparison only when the SAS SSD query shows rows. While it reads zero, the listings we match allow no SAS SSD against NVMe price comparison on Amazon.co.uk.

So the gap between the two floors belongs to the drive class. A low figure in the SAS table is the price of a hard drive, and nothing in these tables shows SAS making storage cheaper or NVMe making it dearer, because one table holds hard drives and the other SSDs. A 1.92 TB, 3.84 TB or 7.68 TB NVMe drive has a like-for-like SAS partner only when SAS SSD rows exist, so use the Capacity column and treat every other row as a different product.

One limit on the NVMe side: a listing with no interface recorded cannot match, so a drive missing from the table may still be on sale.

SAS or NVMe: the link and the drive are separate questions

The SCSI Trade Association lists dual-port features for SAS, yet Kioxia's current NVMe tables also list dual x2, so two ports alone do not settle the choice. And one interface spans very different hardware: a dual-port 12 Gbit/s Toshiba hard drive and a 22.5 Gbit/s Kioxia SSD both count as SAS. The word names the link. It does not tell you whether a disk or flash sits behind it.

SAS vs NVMe speed and performance: what makers state

The one matched pair we hold comes from Samsung. It quotes 4,300 MB/s sequential read for the PM1653, a dual-port 24G SAS SSD, and up to 6,800 MB/s for the PM9A3, a PCIe 4.0 NVMe SSD. That puts NVMe about 1.6 times ahead on sequential reads, at those generations. These are maker-quoted peak figures and not our tests, so treat them as a reference point.

SAS SSD vs NVMe performance goes no further than that here. We do not hold a matching pair of SAS and NVMe IOPS figures, so we print no IOPS comparison. We hold no latency number either: NVM Express's line that NVMe was designed for high bandwidth and low latency is a design aim, not a measurement.

Generation moves the answer too. Kioxia's current NVMe tables list PCIe Gen5 x4, and Micron's data-centre line runs from PCIe Gen4 on the 7450 to PCIe Gen6 on the 9650, so a 1.6 times result from one Samsung pair does not transfer to other drives.

A SAS hard drive is a different case again. WD's sheet gives the 24 TB Ultrastar DC HC590 in SAS a sustained 287 MB/s, and Seagate's gives its 12 TB to 24 TB SAS Exos models 285 MB/s at the outer diameter, against Samsung's up to 6,800 MB/s for the PM9A3. These are maker figures for different products: the distance between them is a hard drive against an SSD, not SAS against NVMe. Toshiba's 12 Gbit/s is a link rate, not a drive speed.

SAS vs NVMe connector and bay shape

We hold no connector document for SAS or NVMe, so this section names no pin layouts and makes no cable or backplane claim. What makers do state is shape. Kioxia lists its PM Series SAS SSDs in 2.5-inch 15 mm. Its CM Series NVMe SSDs come in E1.S, E3.S and 2.5-inch, and Samsung's PM9A3 in E1.S, U.2 and M.2. Kioxia lists CM7, CM9 and LC9 in 2.5-inch, the size class of its PM Series; it makes no statement that they fit the same bay.

Size is not proof of connection. NVMe is defined for PCI Express attached storage, so a 2.5-inch NVMe drive still needs a path to PCIe. Your server's documentation is the place to confirm what each bay is connected to, and we name no server here because we hold no document for one.

SAS or NVMe: which question are you asking?

• Your bays reach PCIe and sequential reads matter most: the NVMe table, keeping in mind that Samsung's figures are for two specific drives.
• You are filling a shelf with many drives: SAS topologies are built for many host connections to thousands of targets, and SAS hard drives ranks that side, new and used apart.
• You need two paths to one drive: SAS lists native failover and dual ports, and some NVMe drives list dual x2, so check the exact part with its maker.
• You want a SAS SSD specifically: the SAS SSD query reads 0 rows at this refresh. At zero, this page has nothing to offer you to buy, and the maker figures above are all it holds.

For SAS vs SATA vs NVMe, Samsung's maker-quoted peaks for sequential read are 550 MB/s on the PM893 (SATA), 4,300 MB/s on the PM1653 (SAS) and up to 6,800 MB/s on the PM9A3 (NVMe). They are maker peaks for three products, not Amazon.co.uk listings. The SAS and SATA half has its own tables and controller rule at SAS vs SATA, and flash on its own is ranked on enterprise SSD.