Problem with upgrade to 10.1

[Barry Friedman]

After upgrade from 10.0 to 10.1 using freebsd-upgrade the system failed to
boot.  Investigating revealed that one of the devices in fstab no longer
appeared to exist.

The disk configuration is a Dell Raid system with the primary data disk
located on the first raid device and the bootable system on the second
i.e.
cat /etc/fstab
# Device        Mountpoint      FStype  Options Dump    Pass#
/dev/amrd1p2    /               ufs     rw      1       1
/dev/amrd1p3    none            swap    sw      0       0
#/dev/amrd0p1   /disk0          ufs     rw      2       2

I was able to comment out the line for /disk0 and now the system boots.

However /dev/amrd0p1 no longer exists although /dev/amrd0 does.

gpart  show -lp
=>        63  1171783617  amrd0  MBR  (559G)
          63  1171783617         - free -  (559G)

=>       34  286515133    amrd1  GPT  (137G)
         34        128  amrd1p1  (null)  (64K)
        162  276823936  amrd1p2  (null)  (132G)
  276824098    8388608  amrd1p3  (null)  (4.0G)
  285212706    1302461           - free -  (636M)

Seems to indicate that the amrd0 raid array has been converted to MBR

So my questions are:

1)  Why did this happen?
2)  Is it possible to recover the data disk?

Regards,
--
Barry Friedman
Emax Computer Systems Inc., 480 Tweedsmuir Ave., Ottawa, Ont. Canada K1Z 5N9
bfriedman at emax.ca  613-725-3198  Mobile: 613-261-0767