Please note that bootint with rootdelay=20 does not solve the problem. It only masks it.
1. If I attempt a fresh USB install of jessie, when md0 is correctly built before the install, the process of doing the fresh install breaks md0. When it gets to grub install, components of md0 are missing (even though all six components were present before the install). And grub-install fails. At this point it is impossible to complete the install and produce a bootable system. 2. If I do a fresh minimal USB install of wheezy, rebuilding md0 in the process, and then do a dist-upgrade to jessie, I can manually add rootdelay=20 in grub and boot into jessie with all six components of md0 present. But if I do so, then after boot, if I do dpkg-reconfigure pc-grub, doing that gives errors, drops components of md0, precludes me from adding them back, fails to install grub, and leaves the machine in an unbootable state. I fear that there is a problem writing to disk. Even if I boot with rootdelay=20, unless the kind of writes that dpkg-reconfigure pc-grub does are different, doing ordinary writes to disk may also corrupt the disk. Please let me know what new information you would like me to gather. Jeff (http://engineering.purdue.edu/~qobi)