Refurbished SAS Hard Drives

SAS drives by spindle speed

Spindle speed decides what a SAS hard drive is for. Average rotational latency is the time the platter takes to make half a turn, so it shrinks as RPM rises, while capacity per drive moves the other way: in Seagate's enterprise range the biggest 15K drive holds 900GB and the biggest 10K drive 2.4TB, and the 7.2K drives are the capacity tier.

Reliability barely separates the classes: Seagate rates its 15K, 10K and 7,200 RPM enterprise drives at the same 0.44% annualized failure rate, and its 7,200 RPM drives at 2 million hours MTBF and 550TB of workload a year.

Each class also has its own page: 15,000 RPM SAS drives, 10,000 RPM SAS drives and nearline SAS (NL-SAS) drives.

SAS or SATA: what the interface changes

SAS gives a hard drive two ports, full-duplex links and a deeper command queue; SATA gives it one half-duplex port. Seagate's paper on the two interfaces and its enterprise data sheets compare them:

SAS generations on one controller

A SAS link runs at the fastest rate both ends support, so generations mix: Broadcom's 12Gb/s HBAs negotiate SAS at 3, 6 or 12Gb/s and SATA at 3 or 6Gb/s.

Sector formats and self-encrypting versions

Match the sector format and security build to the drive you are replacing. Seagate pairs 512-native models with advanced-format models that ship in 512e mode and can be reformatted to 4K native; its security builds are standard, self-encrypting (SED) and FIPS 140-2, and SED models may need a TCG-compliant controller. The 10K SAS drives page compares 512n, 512e and 4Kn.

Carriers and hot-plug bays

Check each listing for whether the drive ships bare or in a carrier. Dell and HPE use their own carrier designs, so reuse the old drive's carrier or order one from hard drive caddies and trays. Seagate lists hot plug among the SAS interface features, so a hot-plug bay takes a swap without a shutdown. Carriers also follow bay size: see 2.5-inch and 3.5-inch hard drives.

Servers and controllers that run SAS

A SAS drive needs a SAS controller. Seagate's guidance runs one way: a SATA drive can go on a SAS controller, but a SAS drive cannot go on a SATA controller. Dell lists 12Gb/s SAS and 6Gb/s SATA drives for the PowerEdge R740 and R740xd, behind either a PERC RAID controller or a non-RAID HBA, and HPE's DL380 Gen10 QuickSpecs class SAS drives as Enterprise at 10K and 15K and Midline at 7.2K. Interface trade-offs are in our SAS vs SATA guide, and array layouts in our RAID 5, RAID 6 and RAID 10 comparison.

Every SAS drive comes with an Enterasource warranty, the length given on each listing. Controllers for these drives are listed under SAS HBAs and server RAID controllers, and the servers themselves under Dell PowerEdge and HPE ProLiant. Browse every interface on server hard drives, or compare SATA hard drives.

SAS drive questions

What is a SAS drive?

SAS drives are hard drives and SSDs built for Serial Attached SCSI, the serial interface that carries SCSI commands between a server's controller and its drives at 3, 6 or 12 Gb/s, and at 24G in the newest generation. A SAS hard drive has two ports, each with its own address, so the server can reach it over two paths. SAS backplanes also take SATA drives, but a SAS drive runs only behind a SAS HBA or a SAS RAID controller, such as a Dell PERC.

Can I use a SAS drive in a SATA server?

Only if the server has a SAS controller. A SAS drive will not run from a SATA-only controller or a motherboard SATA port, because SATA hosts cannot drive the SAS protocol. A SAS RAID controller or SAS HBA behind a SAS backplane runs SAS and SATA drives side by side.

Can I mix SAS and SATA drives in one RAID array?

On one controller, yes; inside one virtual disk, no. Dell's PERC 10 user guide does not support mixing SAS and SATA drives, or hard drives and SSDs, within a virtual disk, though it supports mixed spindle speeds and link rates when the interface and media match. Build one virtual disk per drive type.

Is SAS faster than SATA?

On the link, yes: Seagate gives SAS 12Gb/s per link against 6Gb/s for SATA, full-duplex transfers, two ports and a queue of up to 256 commands. At the platter, RPM decides: Seagate's 7,200 RPM drive averages 4.16 ms latency in both builds, while its 10K and 15K drives, at 2.9 and 2.0 ms, are SAS only.