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