Comparing SAS and SATA, Enterprise and Desktop Hard Drives for Server RAID Systems

Documentation

Product Comparison

000005782

07/11/2022

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This page offers key information to help you understand the differences between the two technologies. As technology rapidly advances, the information on this page may be dated and not comprehensive.

The table below provides system integrators with the key information they need to determine their hard drive requirements.

SAS vs. SATA

Requirement SAS SATA
Operational Availability 24 hours/day - 7 days/week 8 hours/day - 5 days/week
Workload 100% 10–20%
Cost Sensitivity Moderately sensitive to cost Sensitive to low cost
Performance Latency and Seek 5.7 msec @ 15K rpm 13 msec @ 7200rpm (or smaller)
Command Queuing and Reordering Full Limited
Rotational Vibration Tolerance Up to 21 rads/sec Up to 5 to 12 rads/sec
Typical I/Os per sec/drive 319 77
Duplex Operation Full Half
Reliability Bad Sector Recovery Typical timeout is 7–15 seconds only. Timeouts are up to 30 seconds.
Misalignment detection Dedicated Servo and data path processors Single combined servo/data path processor or none
Vibration Sensors RV Compensation Feedback Mechanism No RV Compensation
Variable Sector Size Uses a 528-byte sector and allow the I/O controller Does not use a variable sector size (locked at 512 bytes)
MTBF 1.2M hours at 45 degrees C 700K hours at 25 degrees C
Internal Data Integrity Checks End to End Limited, none in the memory buffer
Maximum Operating Temperature ~60 degrees C ~40 degrees C
Warranty ~5 years ~ to 3 years
Features Spindle Motor Higher RPM
Tighter run-out
Spindle anchor at both ends
Moderate to lower RPM
Lower specification for run-out
Spindle anchored at one end
Media Full media cert Lower media specification and density
Head Stack Assembly Structural rigidity
Lower inertial design
Lighter weight design
Higher inertial design
Actuator Mechanics Larger magnets
Air turbulence controls
RV sensors and closed loop RV
suppression
Smaller magnets
No air turbulence compensation
No RV sensors or suppression - limited to
servo wedge track alignment
Electronics Dual processors
(dedicated servo and data path processors)
Performance optimization
Advanced error handling
Advanced firmware algorithms
Single processor

No performance optimization
Standard error handling
Standard Firmware algorithms
Customization FW Code Extensive Limited
Variable Sector Sizes Yes No
LEDs Yes No
Note
  • Vendor implementations of these features vary between drive models. (Typical MTBF, operating temperature, and operating rotational vibration vary depending on the manufacturer). Generally the high end of the feature spectrum includes enterprise-class SAS hard drives, and the low end includes desktop-class SATA drives. Enterprise-class SATA drives fall somewhere in between.
  • SAS and SATA drives should not be used together in the same RAID array and should not be mixed in the same backplane.

Enterprise-class versus Desktop-class Hard Drives (PDF) icon
Size: 284 KB
Date: April 2016
Revision: 2.0

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