Can I buy SAS drives on my SATA Controller?
What is the compatibility and restrictions about mixing these?
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3 Answers
From Wikipedia:
SAS offers backwards-compatibility with second-generation SATA drives. SATA 3 Gbit/s drives may be connected to SAS backplanes, but SAS drives may not be connected to SATA backplanes.
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So, if I want to take advantage of SAS drives, and their speed over SATA, I will need a special SAS controller - standard SATA doesn't provide that?– JasonAug 10, 2009 at 14:56
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The SAS protocol supports tunneling SATA commands over it. Thus, a SAS controller can communicate with SATA drives or SAS drives. However, it doesn't go the other way. SATA controllers can only communicate with SATA devices.
Supporting mixed drive types is a vendor-by-vendor, device-by-device thing. Generally, this is not well supported and will cause both drives to run at the speed of the slowest drive. Support will likely improve in the future.
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1Most hardware support both (mixed) quite well. Generally they will not run as the speed of the slowest drive, as the SAS backplane uses PtP connections for everything, each link generally operates at the highest speed support by both endpoints. YMMV.– Chris SFeb 22, 2010 at 21:30
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That's true when the drives are operating as separate volumes. When I wrote my comment I was thinking that these mixed drives were all used in the same RAID volume, but I neglected to mention that :(– btaFeb 22, 2010 at 23:31
It depends on the controller, some HP ones support both but you'll have to check with your vendor specs.
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-1. Yes, guess why - that are SAS controllers. He specifically asks about SATA controllers.– TomTomMay 31, 2013 at 19:38