Ross Walker wrote: > On Aug 14, 2009, at 12:48 PM, Robert Nichols > <rnicholsNOSPAM at comcast.net> wrote: > >> Ross Walker wrote: >>> On Fri, Aug 14, 2009 at 5:00 AM, Chan Chung Hang >>> Christopher<christopher.chan at bradbury.edu.hk> wrote: >>> >>> Question now is, was the first sector of partition 1 damaged (was it >>> 63 or 64 sectors dd'd)? >>> >>> If so it will require a more tricky procedure to fix. >> No, the ext2 file system does not use the first 1K block of the partition. >> That space is left free for a boot loader. The first super block of the >> file system is the 2nd 1K block of the partition, and even if that gets >> overwritten it is easily recovered from one of the backup super blocks. > > I did not know that, good information. > > So stage2 is written in first 1k of the partition? No, nowhere near enough room. Just stage 1 goes into the first sector. The second sector is unused. Stage 1 then loads the fs-specific stage 1.5 from absolute sector numbers on the disk. Stage 1.5 then loads stage 2 from the file system. (Yes, if the *_stage1_5 files get moved on the disk, you have to re-run the GRUB installer.) The only time more than the 446-byte stage 1 gets installed is when installing GRUB in the MBR or in the boot sector of a logical drive in the extended partition. There, there can be a full track available, which is enough room for the appropriate stage 1.5, but not for the 100+ KB of stage 2. > Ah but I believe the OP has the partition setup as a LVM PV. Question > is does LVM leave the first 1k free for a stage2 boot loader? > > And if the LVM metadata is corrupt is there a second copy at the end > of the PV? No idea. I don't use LVM. Having a known recovery path if things get munged is more important to me than the features of LVM. -- Bob Nichols "NOSPAM" is really part of my email address. Do NOT delete it.