Seems like HDD failure. Try to read this disk in another computer. If
superblock is damaged -- you may try to recover form backup superblock
(e2fsck -b).

21/10/2013 05:52 -0700, Henrique C. S. Junior wrote:
> After a power failure in my building, my SL 6.4 (x86_64) is
> experiencing a kernel panic in the first stages of booting.
> Error messages suggests that a serious problem occurred with my Ext4
> filesystem in /dev/mapper/VolGroup-lv_root.
> Here are the error messages aftes the kernel panic:
> 
> ata3.00: status: { DRDY ERR }
> ata3.00: error: { UNC }
> ata3.00: exception Emask 0xoSAct 0x0 SErr 0x0 action 0x0
> ata3.00: BMDMA stat 0x25
> ata3.00: failed command: READ DMA
> ata3.00: cmd c8/00:00:c0:86:14/00:00:00:00:00/e3 tag 0 dm 131072 in
>          res 51/40:cf:e8:86:14/00:00:00:00:00/e3 Emask 0x9 (media
> error)
> 
> ata3.00: status: { DRDY ERR }
> ata3.00: error: { UNC }
> JBD: Failed to read block at offset 6886
> EXT4-fs (dm-0): error loading journal
> mount: wrong fs type, bad option, bad superblock
> on /dev/mapper/VolGroup-lv_root,
>        missing codepage or helper program, or other error
>        In some cases useful info is found in syslog - try
> dmesg | tail or so
> 
> Rescue disk says that I "don't have any Linux partitions" and I need
> to rescue, at least, two MySQL databases in this server.
> Can someone, please, provide some help with this case?
>  
> ---
> Henrique C. S. Junior
> http://about.me/henriquejunior
> Química Industrial - UFRRJ
> Prefeitura Muncipal de Paracambi
> Centro de Processamento de Dados
>