[PATCH] First Attempt at DDF v1 Support for dmraid

Darrick J. Wong djwong at us.ibm.com
Fri Apr 28 04:31:14 UTC 2006

Hi all,

Linked below is a very preliminary patch to enable SNIA DDF v1 support
in dmraid.  At least in theory, linear volumes, RAID 0, 1, 4 and 5
support should be working, though at the moment I've only managed to
test RAID 0 and 1.  I have three Adaptec SAS/SATA RAID controllers that
write metadata in DDF format--aic94xx HostRAID, an Adaptec 2410SA SATA,
and a ServeRAID 8i card.  Note, however, that there are a few areas
where these cards seem to go a bit out of spec; I've attempted to
capture and make note of these areas in the code.

Like last time with HostRAID support, my rudimentary tests involve first
booting the Adaptec controller, stamping out partitions, filesystems and
various data, and removing the controller.  Then, I boot back up and see
how far I get with mounting the array, fscking, and comparing the data
to the originals.  I've done this enough times without data loss to
conclude that it's working all right, though I've yet to try out any
truly thorny scenarios.

As noted by the numerous FIXMEs in the patch, there's still a fair
amount of work to do in terms of making the driver more robust.  For
example, I don't check the table CRCs at this point, stackable RAIDs are
not supported, and it's theoretically possible (though the Adaptec
controllers don't seem to allow this) to cut up a disk and put various
parts in different arrays.  I'm not even really sure how to express
multiple disk to multiple array relations in dmraid, actually. :)

Also, if anyone else has a SW RAID controller that uses DDF, your
mileage may vary.  Please tread carefully.  96KB patch:


I also added CVT64 to byteorder.h to facilitate byte swapping of 64-bit

Questions?  Comments?

Heinz, if you'd like metadata samples, I'll send you the (somewhat
large) tarballs off-list.


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