SAS vs SATA Hard Drives: What Amazon.co.uk Lists and What the Interface Changes

SAS vs SATA hard drive prices on Amazon.co.uk

Both tables below use one filter: enterprise-class 3.5-inch hard drives in stock on Amazon.co.uk, with the interface as the only difference. At this refresh the SAS table has 48 rows and its lowest figure is £24.75/TB, from Synology HAS5300 HAS5300-8T 8 TB Hard Drive (used). The SATA table has 71 rows and its lowest figure is £20.49/TB, from Seagate Exos 26TB Internal Hard Drive (used).

Those two floors are not a SAS premium or a SATA discount. They can be different capacities, different makers and different conditions, because new and used offers share each table. A gap between two floors measures which listings happen to exist, so we print no percentage.

To get a usable answer, pick one capacity, find it in both tables, keep to the same condition and, if you can, the same maker line. Where one line appears on both sides, the gap you see is close to a real difference between interface versions. Where it appears on one side only, Amazon.co.uk has no comparison to offer at this refresh. A listing with no interface recorded cannot match either table, so a blank here is not proof of no stock.

SAS vs SATA interface: what belongs to the link and what to the drive

It is easy to credit the interface with what belongs to the drive class. Toshiba, Seagate and WD make the split testable, because each sells one enterprise line in both interfaces. The rows on controller, connector, ports and link change with the interface. The rows on workload, warranty, MTBF and sustained rate read the same on both sides.

So workload, warranty and MTBF are properties of the drive line in these cases, and the SAS label earns none of them. Comparing a SATA drive from one class with a SAS drive from another tells you about the classes. That is why both tables at the top of this page filter on the same class. The SCSI Trade Association lists native failover and dual-port features for SAS, and those belong to the interface.

SAS vs SATA connector and cabling

Seagate describes the connector difference in one line: SATA separates power and data, and SAS unifies them. Its installation instructions add that each disk drive has its own cable that connects directly to a SAS host adapter, and that the SAS connector is normally located on a SAS backpanel. A SAS drive can work alongside SATA drives only where the motherboard or a host adapter supports both interfaces, so the machine decides whether a mixed set is possible.

At larger scale, the SCSI Trade Association says SAS topologies carry SATA devices through a tunnelling protocol, with many host connections to thousands of target devices in one topology. We have not found a document showing that a converter gets a SAS drive running on a SATA port, and Seagate's rule points the other way, so this page recommends none.

SAS vs SATA speed: the link is not the drive

On hard drives the headline numbers are link rates. Toshiba's MG line offers 6 Gbit/s SATA and 12 Gbit/s SAS. WD's data sheet for the 24 TB Ultrastar DC HC590 gives an interface rate of 600 MB/s on SATA and 1200 MB/s on SAS, and a sustained rate of 287 MB/s (274 MiB/s) on both versions. These are maker figures, not our tests. On that drive the link doubles and the sustained figure does not move.

SSDs are where the interface starts to set the ceiling. Kioxia lists its PM7 SAS SSD as SAS-4 at 22.5 Gbit/s, well above SATA's 6 Gbit/s. Samsung's PM893 SATA SSD tops out at 550 MB/s sequential read and 520 MB/s sequential write. Those are maker figures for two separate products, not Amazon.co.uk listings.

SAS vs SATA SSD: what Amazon.co.uk lists

SSDs need their own check. The SATA enterprise SSD table has 13 rows, lowest £134.89/TB from Samsung MZ7LM3T8HCJM-00003 (used). The matching SAS SSD query returns 0 rows at this refresh, and we print no table for it. While that figure reads zero, a SAS vs SATA SSD price comparison on Amazon.co.uk has only one side, and the SAS half of this page is hard drives alone. A broader view of flash is on enterprise SSD.

SAS vs SATA for NAS: check the controller, not the label

The same rule decides a NAS. If its controller is SATA only, a SAS drive cannot be plugged into it, whatever the price per TB says. SATA drives may go on a SAS controller, so a SATA drive is the one that works in both cases.

We have not found a document tying these tables to a particular NAS, so we name no model. Check the drive list from your NAS's maker for the interface it names. Seagate's sheet prints two ports on its SAS models and one on its SATA models. Whether a chassis uses the second port is a question for its maker.

SAS vs SATA vs NVMe: a separate question

This page holds no NVMe figures. The three-way question splits in two: the SAS and SATA half is above, and Samsung's peak figures for a SATA, a SAS and an NVMe SSD sit in one sentence on SAS vs NVMe. To shop one interface without the comparison, SAS hard drives and SATA enterprise hard drives rank each side with new and used offers apart.