SAS vs SATA
Posted on 2010-09-12
Hi, I was doing some Sunday afternoon reading and starting thinking about SAS again. It got me thinking maybe I the reason I have had so many HDD failures in RAID 1 & RAID 5 on some of my servers is due to moving to SATA rather than sticking with SAS.
So, I would like to take a poll to find out who all has made the switch to SATA on their servers?
We have nearly moved completely over to SATA, due to cost-savings, but now I am wondering if we should at least rethink our very critical servers (SQL, Exchange, Web) should be SAS for more reliablity.
Here is what the wiki says about SAS vs SATA :
SAS vs SATA
This section does not cite any references or sources.
Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (July 2009)
SAS is full-duplex, SATA is half-duplex.
Systems identify SATA devices by their port number connected to the host bus adapter, while SAS devices are uniquely identified by their World Wide Name (WWN).
SAS protocol supports multiple initiators in a SAS domain, while SATA has no analogous provision.
Most SAS drives provide tagged command queuing, while most newer SATA drives provide native command queuing, each of which has its pros and cons.
SATA uses the ATA command set; SAS uses the SCSI command set. ATA directly supports only direct-access storage. However SCSI commands may be tunneled through ATA for devices such as CD/DVD drives.
SAS hardware allows multipath I/O to devices while SATA (prior to SATA 3Gb/s) does not. Per specification, SATA 3Gb/s makes use of port multipliers to achieve port expansion. Some port multiplier manufacturers have implemented multipath I/O using port multiplier hardware.
SATA is marketed as a general-purpose successor to parallel ATA and has become[update] common in the consumer market, whereas the more-expensive SAS targets critical server applications.
SAS error-recovery and error-reporting use SCSI commands which have more functionality than the ATA SMART commands used by SATA drives.
SAS uses higher signaling voltages (800-1600 mV TX, 275-1600 mV RX) than SATA (400-600 mV TX, 325-600 mV RX). The higher voltage offers (among other features) the ability to use SAS in server backplanes.
Because of its higher signaling voltages, SAS can use cables up to 10 m (33 ft) long, SATA has a cable-length limit of 1 m (3 ft) or 2 m (6.6 ft) for eSATA.
So, chime in and let me know what you think about this debate.
Thanks for your time.