As an example of "why you care", let's say that your player has been reporting a media error like this:

empeg:/empeg/bin# cat /dev/hda > /dev/null
hda: read_intr: status=0x59 { DriveReady SeekComplete DataRequest Error }
hda: read_intr: error=0x40 { UncorrectableError }, LBAsect=115459753, sector=115459753
end_request: I/O error, dev 03:00 (hda), sector 115459753
cat: /dev/hda: Input/output error

This bad sector can be fixed in-situ with this command:

hdparm --repair-sector 115459753 /dev/hda

---------------------------------------------------

Or perhaps you've used smartctl to check for problems, and seen a report such as this:

./smartctl.bin -l error /dev/hdc
smartctl version 5.33 ...
...
Error 0 occurred at disk power-on lifetime: 3887 hours (161 days + 23 hours)
When the command that caused the error occurred, the device was in a vendor specific state.

After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
51 01 01 00 00 43 a1 Error: UNC, IDNF, AMNF at LBA = 0x01430000 = 21168128

Commands leading to the command that caused the error were ...


The "UNC, IDNF, AMNF at LBA = 0x01430000 = 21168128" line indicates a bad sector (UNCorrectable, ID Not Found, Address Mark Not Found) at 21168128. which can now be repaired with this quick command:

hdparm --repair-sector 21168128 /dev/hdc


Enjoy.