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Is it possible to use SATA drives when you have a SAS shared backplane to be able to address the drives?

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What type of server, hardware, controller and/or JBOD enclosure are you using? –  ewwhite Nov 23 '12 at 14:52

3 Answers 3

Yes. It's definitely not ideal, but yes, you can.

Scenarios...

  • Shared backplane behind a SAS expander. Not good.
  • Shared backplane with dedicated 4-lane SAS connectors (e.g. a Dell or HP server's internal drive bays with 1:1 port controller port to disk bay mapping). Okay.

I tell people to just use nearline SAS instead of SATA these days, just to avoid any issues. Expanders tend to cause more problems in these mixed scenarios.

Technical explanation in detail.

It's when you add SAS expanders (and SATA Tunneling Protocol) to the mix that you start encountering weird errors with misbehaving SATA disks. SATA simply isn't designed with a switching fabric in mind, and it looks like firmwares still aren't robust enough to deal with command tunneling reliably in the presence of errors.

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SIMPLE answer: yes.

COMPLEX answer: Yes, IF the SATA drives actually behave correctly - some do not. Too few checks, so you get issues.

I run a 24 slow SA backplane full with SATA drives (SSD, Velociraptors) and I DID have a share of Problems under load. SSD Firmwareupdates got them under control.

http://www.adaptec.com/blog/?p=1951

isa blog post about a similar experience ;)

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It's depend of SAS architecture. If your backplane have connector type SFF 8482 it is compatible. See: http://en.wikipedia.org/wiki/Serial_attached_SCSI#Architecture

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