On Saturday 25 Aug 2012 12:13:41 Florian Philipp wrote:
> Hi list!
>
> I've just completed migrating my system from one hard disk to another.
> Although the new disk reports 512 byte blocks just like the old one, I
> thought it would be a good idea to re-align the partitions anyway. I've
> done it this way:
>
> 1. Create new partitions with gparted, at least as large as the old ones
> (rounded up to full MiB).
>
> 2. `dd` from the old to the new disk.
>
> 3. `resize2fs` to match the new sizes.
>
> 4. Install grub ("root (hd1,4); setup (hd1); setup (hd1,4)")Why did you run setup twice? Once to install to the MBR of the second disk and once to install on the boot record of the 5th partition ... :-/ > 4. Swap disks and reboot. > > Unfortunately, the system failed to find the boot loader. There was no > grub error. The disk was simply skipped, as if it was unformatted. > > The following steps were taken: > > 1. Verified that the `dd`ed partitions were sane. > > 2. Reinstalled grub from live-CD chroots several times. > > 3. Installed grub on a memory stick and booted from that. > > At this point, my partition table looked like this: > > Number Start End Size Type File system Flags > 1 1049kB 316MB 315MB primary ntfs > 2 316MB 750GB 750GB extended > 5 317MB 424MB 107MB logical ext2 boot > 6 425MB 22.4GB 22.0GB logical ext3 > 7 22.4GB 28.9GB 6441MB logical linux-swap(v1) > 8 28.9GB 750GB 721GB logical > > The first logical partition was the boot partition. The first primary > partition was a laptop-specific recovery partition. This setup was > identical to the old one except that I removed a primary partition which > resided /after/ the end of the extended partition. You didn't need to remove it. You could have entered x (extra functionality) and then f (fix partition order). Write the new table and run partprobe to see what the kernel sees the partitions as now. Another thing to check is what grub sees: grub> find /boot/grub/stage1 (hd0,9) The above is from a laptop of mine, where the linux boot partition is on partition 10. > At this point, I've reformatted the first primary partition as ext2 and > moved boot to this partition. This solved my problem. > > Now, my question is: Why does this work and the old solution doesn't? > Why can't grub boot from a logical partition when it's MiB-aligned? I've > changed nothing that should affect the MBR. Then why wasn't at least the > stage 1 detected? I've got at least 4 machines with logical boot partitions and all boot fine. Mind you though, the partition order is correct on all of them. I don't know if that had something to do with it. -- Regards, Mick
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