SAS and SATA Hard Disk Drives

SAS and SATA Hard Disk Drives.

Technical Information.

Technical Information Page

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Enterprise Hard Disk Drive Types compared:-

• Serial Attached SCSI (SAS)
• Near Line SAS (NL-SAS)
• Serial ATA (SATA).

SAS Hard Disk Drives.

SAS hard disk drives have rotational speeds of 10K and 15K RPM and offer  relatively faster input output operations per second (IOPS ) per physical disk than standard products.  (relative IOPS are shown in the table below.) Processing performance criteria is why many are willing to purchase  SAS disks even though it means buying many more units  (than SATA or NL-SAS) to meet comparable system capacity  projections.

SAS hard disk drives  have become the standard in enterprise-grade digital storage media.  SAS disks are statistically more reliable in operation than either NL-SAS or SATA disks.

• SAS disks, the BER is generally 1 in 10^16 bits.
• SAS disks have MTBF of 1.6 million hours
• SATA disks have a BER of 1 in 10^15.
• SATA have MTBF of 1.2 million hours.

NL-SAS Hard Disk  Drives.

NL-SAS drives are enterprise SATA drives with a SAS interface, head, media, and rotational speed of traditional enterprise-class SATA drives with the fully capable SAS interface typical for classic SAS drives.

NL-SAS provide command queuing, concurrent data channels and multiple host support.
NL-SAS disks have BER of 1 in 10^15 and MTBF of 1.2 million hours.
NL-SAS rotational speed of 7200 RPM… the same as a typical SATA disks.

NL-SAS helps manufacturers streamline production, and can help end users from a controller perspective, but they are not a replacement for SAS.

SATA Hard Disk Drives.

SATA storage cost per TB outperforms other types of storage. SATA disks do not perform as well as SAS and have fewer enterprise benefits however they remain a mainstay of many organization’s storage system. .


SAS for performance and SATA for capacity. Straddling the two is NL-SAS, which brings some SAS capability to SATA disks, but doesn’t bring the additional reliability found with SAS.

Typical Relative Device Type IOPS :

  • 7200 rpm SATA
  • 10,000 rpm SATA
  • 10,000 rpm SAS
  • 15,000 rpm SAS
  • 75-100 IOPS
  • 15-150 1OPS
  • 140 IOPS
  • 175-210 IOPS
  • SATA 3Gbits
  • SATA 3 Gbits
  • SAS
  • SAS