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 --- 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 >