First boot after BMR restore fails on UNIX platforms
After BMR restore, first boot may fail at Grub if root disk that is originally mirrored across two disks is changed to concatenate layout. In the system setup, root disk was mirrored across 2 disks say c3t0d0 and c4t0d0. In BIOS settings, c3t0d0 is the first disk in boot sequence. During DDR configuration, root disk is changed from mirror to concatenate and mapped on c4t0d0. In BIOS, this disk is the second disk in boot sequence. So, after BMR restore, when system boots for the first time, as c3t0d0 is the first disk in boot sequence AND as "grub signature is still present on this disk as it was mirrored earlier", system tries to boot from the grub on c3t0d0 and then fails to boot as it does not get root file system and other bootable files which are now on c4t0d0.
After BMR restore, during system boot, change the BIOS settings and choose the correct disk for system to boot.