Daniel Ouellet wrote: > Nick Holland wrote: >> the "Use entire disk" question changes no more than 512 bytes on your >> disk. That's the good news. The significance of that 512 bytes is the >> problem. (and while 512 bytes doesn't sound that bad, that's >> 2^(512*8) combinations...so we still gotta do somewhat better than >> random guessing) > > Nick, one question I have reading lots of stuff on google results and > that I want to be sure as my understanding is kind of vague here. > This action replace only the sector for 512 Bytes and would leave the > rest of the cylinder intact right? Or not?
correct. no touchie. The boot loader install process does not touch any of the other sectors on the track or cylinder (or disk ...) > I am asking as I am may making some progress. I found that the GPT, what > ever that is that Apple use form the Intel standard have two copy of it. > > One at the start of the disk and one at the end of the disk and that the > GPT also include the MBR details. A bit more here: > > http://blog.csdn.net/hotsolaris/archive/2008/12/23/3589039.aspx > > The primary GPT with I understand would have been what this OpenBSD > process replace is gone, but then the secondary GPT most likely still > intact. > > Not sure how to read it or even if possible. SO, I will continue the > research on this, but to be sure, only the first 512 bytes and nothing > at all would have been modified right? correct. :) > So, if I can find a way to read the secondary GPT, I might be able to > see what the primary should be and may be recreate it. No clue how yet, > but that appear logical right? just on my way out the door, but in the refit "myths and facts" page, I found reference to a gptsync which seems to copy the EFI stuff to the MBR. This is good. The fact that the rest of the boot code was blown away is bad. You need to carefully restore the boot code of the first sector, then restore the partition info, but the GPT stuff looks like it can save you. Installing the same version of refit to another disk may be a starting point. or maybe not. Again...good luck. Nick.
