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Re: Improperly nested partitions, help needed!
From: |
Lennart Sorensen |
Subject: |
Re: Improperly nested partitions, help needed! |
Date: |
Tue, 21 Sep 2010 16:18:27 -0400 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Tue, Sep 21, 2010 at 09:42:14PM +0200, Svante Signell wrote:
> Yes, if I remember correctly, that's what I did some time ago, when
> installing a new disk for /home.
>
> > If so, then there is a chance that the first sector of sda3 contains
> > the old extended partition table, and grub probe might be detecting that.
> >
> > One way to check would be to do:
> >
> > dd if=/dev/sda3 of=/tmp/sda3.mbr bs=512 count=1
> >
> > Then run 'file /tmp/sda3.mbr'. If it says partition table, then I think
> > you have found your problem.
>
> Yes, you are right:
> # file /tmp/sda3.mbr
> /tmp/sda3.mbr: x86 boot sector; GRand Unified Bootloader, stage1 version
> 0x3, 1st sector stage2 0xdd29b38; partition 1: ID=0x83, starthead 239,
> startsector 63, 35153937 sectors, extended partition table (last)\011,
> code offset 0x48
>
> # fdisk -lu /dev/sda
>
> Disk /dev/sda: 160.0 GB, 160041885696 bytes
> 240 heads, 63 sectors/track, 20673 cylinders, total 312581808 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0xd568d568
>
> Device Boot Start End Blocks Id System
> /dev/sda1 63 7575119 3787528+ 1b Hidden W95 FAT32
> /dev/sda2 * 7575120 230640479 111532680 7 HPFS/NTFS
> /dev/sda3 230640480 234541439 1950480 83 Linux
> /dev/sda4 234541440 312575759 39017160 f W95 Ext'd (LBA)
> /dev/sda5 234541503 240861599 3160048+ 83 Linux
> /dev/sda6 240861663 261878399 10508368+ 83 Linux
> /dev/sda7 261878463 310413599 24267568+ 83 Linux
> /dev/sda8 310413663 312575759 1081048+ 82 Linux swap/Solaris
>
> > If that is what is happening, then it is a question of whether grub-probe
> > made a mistake when it scanned for partitions in something not marked
> > as a valid place to look for partitions. Of course the quick workaround
> > in that case is to clear that sector (assuming the filesystem doesn't
> > use the first sector of the partition, which many filesystems avoid
> > since it is a handy place for boot loaders and such).
>
> You are the Grub developers, you can tell if Grub does the right thing.
I am just a user.
> > If the filesystem does avoid that part of the partition, that would be a
> > good reason an old extended partition table would have survived creating
> > a filesystem.
>
> So the solution is to blank out the first sector of /dev/sda3,
>
> dd if=/dev/null of=/tmp/sda3 bs=512 count=1
>
> to get rid of the warnings? Please confirm the command above is correct.
Not quite.
dd if=/dev/zero of=/tmp/sda3 bs=512 count=1
That should work. /dev/null is for output. You need input and a source
of all zeros.
Probably want to save the original you dumped before on some other media
just in case you need to restore it (although I highly doubt it).
--
Len Sorensen
- Improperly nested partitions, help needed!, Svante Signell, 2010/09/21
- Re: Improperly nested partitions, help needed!, Isaac Dupree, 2010/09/21
- Re: Improperly nested partitions, help needed!, Grégoire Sutre, 2010/09/21
- Re: Improperly nested partitions, help needed!, Lennart Sorensen, 2010/09/21
- Re: Improperly nested partitions, help needed!, Grégoire Sutre, 2010/09/21
- Re: Improperly nested partitions, help needed!, Phillip Susi, 2010/09/22
- Re: Improperly nested partitions, help needed!, Lennart Sorensen, 2010/09/22
- Re: Improperly nested partitions, help needed!, Grégoire Sutre, 2010/09/22
- Re: Improperly nested partitions, help needed!, Lennart Sorensen, 2010/09/22
- Re: Improperly nested partitions, help needed!, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/09/22
- Re: Improperly nested partitions, help needed!, Brendan Trotter, 2010/09/22
- Re: Improperly nested partitions, help needed!, Vladimir 'φ-coder/phcoder' Serbinenko, 2010/09/22