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 at cedrat.com - http://www.cedrat.com > >> -----Message d'origine----- >> De : centos-bounces at centos.org >> [mailto:centos-bounces at centos.org] De la part de Edward Diener >> Envoyé : 3 août 2010 06:08 >> À : centos at 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. >> >> _______________________________________________ >> CentOS mailing list >> CentOS at centos.org >> http://lists.centos.org/mailman/listinfo/centos