blk2scsa [PSARC/2007/654 FastTrack timeout 11/21/2007]

[Garrett D'Amore]

Artem Kachitchkine wrote:
>
>> I'm not sure about ZFS, but it is good enough for sd(7D) with PCFS.
>
> IMO the proposal is incomplete without a clear statement about ZFS, 
> even it it's "unsupported", though I really hope for the opposite: USB 
> storage is the dumbest storage I've ever encountered (so far), yet you 
> can put ZFS on it.
>
> I think the only sure way is to try. Given that the estimated 
> engineering effort for this entire project is 1 engineer-week, I 
> suppose it'd take a couple more days to figure this out.

Yes, I intend to try it out.  I'm not specifically targetting ZFS, but I 
can't see why it wouldn't work, other than the device id concern raised 
below.
>
>> One possible area of concern for ZFS is device id functionality.  The 
>> devices I'm dealing with don't have device identifiers that live 
>> within the SCSI namespace.  (Generally they do have a vendor id, 
>> product id, and serial number... but these are allocated from an 
>> entirely different namespace.)
>
> AFAIK in that case a fabricated devid will be stored in the hidden 
> area of the disk. The same problem exists with USB, see "6422928 devid 
> support is needed for usb harddisk".

If I read the code in sd correctly, this won't be done for removable 
media.  So while it isn't a problem for the blk2scsa framework, it is a 
problem for SDcard media.

Its possible that I'll need to figure out a solution here, I'm not sure. 

    -- Garrett