bug#18019: bug-parted Digest, Vol 140, Issue 9

[Brian C. Lane]

On Mon, Jul 14, 2014 at 01:11:26PM -0400, Rod Smith wrote:
> All that said, there is a further complication, and this one isn't parted's
> fault: The 0xDA type code that's suggested by the mdadm man page is NOT
> specific to Linux RAID. According to
> http://www.win.tue.nl/~aeb/partitions/partition_types-1.html, it refers to
> "non-FS data"; and according to
> https://en.wikipedia.org/wiki/Partition_type, it can be that or a Powercopy
> backup. There may be other specific tools that use it, too. Thus, I'd be a
> little wary of just switching 0xFD to 0xDA as the MBR RAID flag in parted.
> IMHO, what's needed is some coordination between mdadm, parted, fdisk, and
> gdisk authors to settle on a standard for this.

I don't think anyone is suggesting a change to the raid flag. I was
planning on adding support for arbitrary values so that anything can be
set instead of playing whack-a-mole as things change.

The compelling reason for the change, other than just following mdadm's
suggestion is Doug's example scenario from the bz entry:

"It's possible, although it means you have a broken setup, that you
could have a version 1.1 or 1.2 superblock and a version 0.90 on the
same device, and kernel autodetect could assemble it as a version 0.90
device and corrupt the real device.  Likewise, if you use 0x83, then the
kernel filesystem and udev filesystem detection code might find
something you don't want found."

-- 
Brian C. Lane | Anaconda Team | IRC: bcl #anaconda | Port Orchard, WA (PST8PDT)