Driven by the current price difference between SATA and SAS disks on one side and the potentially bad behaviour of SATA disks in bigger storage arrays on the other side, I have found so-called SATA-to-SAS interposer cards.
Advertised as "seamlessly adding SAS capabilities to existing SATA disk drives", I wonder if anyone here has had some experience with these or similar products. The major benefits I can identify are the increased cable voltage (if all drives are SAS connected), the ability to power-cycle the drive and multipath (if desired). Obviously the SATA drive will still have to be RAID edition.
The question is: Do these cards indeed increase the overall reliability of a storage system, or will failing SATA disks cause trouble nevertheless?
Edit: I'm not asking for hypothetical answers, only actual experience please.
I'm well aware that the typical 10k SAS drive is more reliable (and better performing) than 7200 SATA drives. But how does a nearline SAS, which is phyiscally the same disk as its SATA counterpart, compare to the SATA version with interposer?
Best Answer
My two cents: If you are concerned about the edge case failures that may occur with SATA hardware (specifically, lousy SATA controllers), spend the money on real SAS disks.
These cards do what they say on the tin: They translate SAS (SCSI) commands to SATA commands, and even implement a few themselves (like power- and spinup-control).
They do nothing else (the drives are still SATA, their performance characteristics are unchanged, their reliability is unchanged, etc.), and they add a new layer of complexity into your environment (They are hardware + software, either of which could fail, have a defect, etc.) -- From my point of view you are increasing your net chance of a failure versus just buying an appropriate SAS drive.