#dmesg |tail
[17355214.876000] SCSI device sda: 12594959 512-byte hdwr sectors (6449 MB)
[17355214.876000] sda: assuming drive cache: write through
[17355214.876000]  sda: [mac] sda1 sda2 sda3 sda4
[17355214.892000] sd 4:0:0:0: Attached scsi disk sda
[17355214.924000] sd 4:0:0:0: Attached scsi generic sg0 type 0
[17355215.544000] Buffer I/O error on device sda4, logical block 0
[17355215.544000] Buffer I/O error on device sda4, logical block 1
[17355215.924000] Buffer I/O error on device sda4, logical block 0
[17355215.924000] Buffer I/O error on device sda4, logical block 1
[17355362.240000] VFS: Can't find an ext2 filesystem on dev sda1.