SATA<->SAS adapters

[Curious.George]

Is there any reason that a SATA drive's contents, when written behind a SAS->SATA adapter, would differ from what those contents would be in the absence of said adapter? (yeah, I realize the adapter maker could do whatever he wants from one side of the adapter to the other but it would be hard, IMO, to rationalize anything other than a straight-thru mapping)

Said another way, if I run the following experiment, how shocked would you be to discover the results were not identical:

• mount SAS-adapted drive
• compute hash (virtually any hash!) of /dev/CHARACTERDEVICEDESIGNATION
• remove adapter
• mount bare SATA drive (same drive as above but without adapter)
• compute hash
• compare hashes

[Of course, this is just an efficiency hack to avoid needing to do a byte-wise compare of the drive to "itself" (cuz the adapter is either there or not!)

[Topcat]

Re: SATA&lt;-&gt;SAS adapters

Shouldnt, its just a pass-through device. SAS vs SATA OTOH, would probably be dependent upon the controller. I'm not sure I understand exactly what you're trying to accomplish here. I run SAS 2.5" HDD's in WD velociraptor 3.5" adapter trays, they're keyed for SAS internally, but SATA externally, so they can be used either in hot-swap trays or on SAS controllers internally without the adapters at all.

[ratdude747]

Re: SATA&lt;-&gt;SAS adapters

Yes, if you had a faulty adapter. But otherwise, any SAS controller can do SATA drives and the only adapters I know of mechanically allow the connection of SATA cables/backplanes to SAS drives (SAS controller/interface chip still needed).

[Curious.George]

Re: SATA&lt;-&gt;SAS adapters

Shouldnt, its just a pass-through device. SAS vs SATA OTOH, would probably be dependent upon the controller. I'm not sure I understand exactly what you're trying to accomplish here. I run SAS 2.5" HDD's in WD velociraptor 3.5" adapter trays, they're keyed for SAS internally, but SATA externally, so they can be used either in hot-swap trays or on SAS controllers internally without the adapters at all.

I'm essentially trying to do something similar thing -- but with SATA drives... letting them appear as SAS to certain machines and SATA to others (at the cost of installing/removing the adapter)

I.e., install the SAS adapter, plug the SAS-ified drive in, use it. Then, at a later date, pull off the SAS adapter and access the data via the SATA i/f without any special "magic" involved.

This lets me port large chunks of data between SAS and SATA systems without having to actually "copy" it (think of it as sneakernet on steroids)

But, it counts on SAS(LBA) always mapping to SATA(LBA). If the adapter scrambled things or reserved space on the medium for <whatever>, this wouldn't work.