I have an internal hard drive in ext4 format that failed.  There are a few 
things I'd like to recover from it.  It wouldn't boot, but I thought maybe 
I could mount it.  No such luck.  In the text below, lines beginning with 
a dollar sign prompt are commands.  There are three commands followed by 
output.  Apparently, the dmesg output might be useful, but I have no idea 
what it means.

Do any of you have experience with this kind of problem?  Is there 
anything I might try next?

TIA,
Mike


$ sudo parted -l /dev/sda | head > shit

Model: ATA ST32000542AS (scsi)
Disk /dev/sda: 2000GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start   End     Size    Type     File system  Flags
  1      1049kB  1992GB  1992GB  primary  ext4         raid



$ sudo mount -t ext4 /dev/sda1 /media/mbmiller/a

mount: wrong fs type, bad option, bad superblock on /dev/sda1,
        missing codepage or helper program, or other error

        In some cases useful info is found in syslog - try
        dmesg | tail or so.



$ dmesg | tail -n19

[168330.232384]  sda: sda1
[169448.936028] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
[169448.936033] ata3.00: BMDMA stat 0x24
[169448.936037] ata3.00: failed command: READ DMA EXT
[169448.936042] ata3.00: cmd 25/00:f8:58:1d:c5/00:00:73:00:00/e0 tag 0 dma 126976 in
          res 51/40:00:1a:1e:c5/40:00:73:00:00/00 Emask 0x9 (media error)
[169448.936045] ata3.00: status: { DRDY ERR }
[169448.936046] ata3.00: error: { UNC }
[169449.048405] ata3.00: configured for UDMA/133
[169449.048439] sd 2:0:0:0: [sda] FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[169449.048442] sd 2:0:0:0: [sda] Sense Key : Medium Error [current] [descriptor]
[169449.048445] sd 2:0:0:0: [sda] Add. Sense: Unrecovered read error - auto reallocate failed
[169449.048447] sd 2:0:0:0: [sda] CDB: 
[169449.048449] Read(10): 28 00 73 c5 1d 58 00 00 f8 00
[169449.048456] blk_update_request: I/O error, dev sda, sector 1942298138
[169449.048470] ata3: EH complete
[169449.048603] JBD2: Failed to read block at offset 8899
[169449.048900] JBD2: recovery failed
[169449.048903] EXT4-fs (sda1): error loading journal