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Hi all!
Doing some tests with CentOS 5.5 on a KVM virtual machine, after doing
the installation, I added a second disk. But when trying to boot from
it, I get the following error:
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root (hd1,0)
Error 21: Selected disk does not exist
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The two disks are Virtio devices that are recognized when booting from
the first disk:
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[root at localhost ~]# fdisk -l /dev/vda
Disco /dev/vda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Unidades = cilindros de 16065 * 512 = 8225280 bytes
Disposit. Inicio Comienzo Fin Bloques Id Sistema
/dev/vda1 * 1 1174 9430123+ fd Linux raid autodetect
/dev/vda2 1175 1305 1052257+ fd Linux raid autodetect
[root at localhost ~]#
[root at localhost ~]#
[root at localhost ~]# fdisk -l /dev/vdb
Disco /dev/vdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Unidades = cilindros de 16065 * 512 = 8225280 bytes
Disposit. Inicio Comienzo Fin Bloques Id Sistema
/dev/vdb1 * 1 1174 9430123+ fd Linux raid autodetect
/dev/vdb2 1175 1305 1052257+ fd Linux raid autodetect
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The idea of these tests is to set up software RAID1 on a running system,
since, as I said in another thread, it seems that Anaconda does not
support installation on degraded RAID.
But I'm not sure if this is a problem of Virtio or that GRUB is not
recognizing the second disk.
I made sure to modify /boot/grub/device.map with the entry for the new
disk:
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[root at localhost grub]# cat /boot/grub/device.map
# this device map was generated by anaconda
(hd0) /dev/vda
(hd1) /dev/vdb
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And the reconfiguration of GRUB on both disks did not give problems:
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[root at localhost grub]# grub --device-map=/boot/grub/device.map
GNU GRUB version 0.97 (640K lower / 3072K upper memory)
[ Minimal BASH-like line editing is supported. For the first word, TAB
lists possible command completions. Anywhere else TAB lists the
possible
completions of a device/filename.]
grub> root (hd0,0)
root (hd0,0)
Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd0)
setup (hd0)
Checking if "/boot/grub/stage1" exists... yes
Checking if "/boot/grub/stage2" exists... yes
Checking if "/boot/grub/e2fs_stage1_5" exists... yes
Running "embed /boot/grub/e2fs_stage1_5 (hd0)"... 15 sectors are
embedded.
succeeded
Running "install /boot/grub/stage1 (hd0) (hd0)1+15 p
(hd0,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
Done.
grub> root (hd1,0)
root (hd1,0)
Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd1)
setup (hd1)
Checking if "/boot/grub/stage1" exists... yes
Checking if "/boot/grub/stage2" exists... yes
Checking if "/boot/grub/e2fs_stage1_5" exists... yes
Running "embed /boot/grub/e2fs_stage1_5 (hd1)"... 15 sectors are
embedded.
succeeded
Running "install /boot/grub/stage1 (hd1) (hd1)1+15 p
(hd1,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
Done.
grub> quit
quit
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Any idea what may be causing the problem?
Thanks in advance for your replies.
Regards,
Daniel
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