Re: Problem with USB-to-SATA adapters (was: AS2105-based enclosure size issues with >2TB HDDs)

Douglas Gilbert
2014-08-30T21:40:40Z

On 14-08-30 05:15 PM, Alan Stern wrote:
> On Fri, 29 Aug 2014, Matthew Dharm wrote:
>
>> Is there an 'easy' way to override the detected size of a storage
>> device from userspace? If we had that, someone could write a helper
>> application which looked for this particular fubar and try to Do The
>> Right Thing(tm), or at least offer the user some options.
>
> You mean, force a Media Change event and override the capacity reported
> by the hardware? I'm not aware of any API for doing that, although it
> probably wouldn't be too hard to add one.
>
> How would the user know what value to put in for the capacity? Unless
> the drive had been hooked up to a different computer and the user
> manually noted the correct capacity and typed it in, it would have to
> be guesswork.

Might another possibility be using the SAT layer to issue
the appropriate ATA command via the SCSI ATA PASS-THROUGH
(12 or 16) command to find out the disk's size. This might
be a possible strategy if READ CAPACITY(10) yields 0xffffffff
for the last sector's LBA and the follow-up READ CAPACITY(16)
fails or yields a truncated value.

Doug Gilbert

BTW Been looking at a USB-to-SATA adapter that uses the
UAS(P) transport. I thought nothing could have worse
SCSI compliance than USB mass storage devices. I was
wrong ...