On 8/3/2010 4:53 AM, Robert Grasso wrote:
Hello,
as for understanding the grub disk and partition numbering scheme, you should read :
info grub
and more specifically the "Naming convention" paragraph.
Your issue is all about understanding this.
Hope this helps
No, it does not help. I understand how grub refers to partitions. On my system the boot partition is /dev/sda10 -> (hd0,9). For some reason grub does not see (hd0,9) as a disk or maybe just hd0 as a disk. In other words, after mounting my partitions off of /mnt/sysimage and switching my root with chroot /mnt/sysimage, grub does not find (hd0,9). Why ?
Robert GRASSO – System engineer
CEDRAT S.A. 15 Chemin de Malacher - Inovallée - 38246 MEYLAN cedex - FRANCE Phone: +33 (0)4 76 90 50 45 - Fax: +33 (0)4 56 38 08 30 mailto:robert.grasso@cedrat.com - http://www.cedrat.com
-----Message d'origine----- De : centos-bounces@centos.org [mailto:centos-bounces@centos.org] De la part de Edward Diener Envoyé : 3 août 2010 06:08 À : centos@centos.org Objet : [CentOS] Manually mounting partitions in "linux rescue" mode
I boot from the installation DVD, with an already existing CentOS 5.5 system on my hard disks. I have separate boot, root, and home partitions. I have moved the boot partition and now I need to re-initialize grub from rescue mode.
Attempting to use 'rescue mode" to automatically mount my system under /mnt/sysimage eventally fails with an error message, which essentially says 'mount error' and nothing else. I am then put at a command prompt as root.
So now I decide to manually mount my partitions at /mnt/sysimage and then do a chroot to /mnt/sysimage. This succeeds and when I look at my files they are there.
I now try 'grub' and the 'grub' shell comes up. I now attempt the 'grub' command:
root (hd0,9)
only to be met with:
Error 21: Selected disk does not exist.
I do not know what this means and how I can correct it. Does anybody know what is going on ?
One thing I am concerned about is that when I booted from the DVD and was eventually put at the command prompt, I saw there were devices in the /dev subdirectory but after I did the chroot, there were no devices in the new root's /dev subdirectory although when I had previosuly booted into CentOS 5.5 on my hard disk off course they were there.
The other thing I noticed is that after the 'chroot' the 'mount' command showed only my root partition mounted on /dev/sdb8 where it actually exists ( along with sysfs and proc which I mounted from the old root ). But despite this there are no subdirectories under the new root's /dev.
I am just trying to re-initialize 'grub' so I can boot my CentOS 5.5 system again. There must be a way to successfully do this from the installation DVD. If somebody can give me the steps to manually mount my partitions and succeed it would be very much appreciated.
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