I have a drive that is reporting that the current pending sectors is "45". I have used badblocks to identify the sectors and I have been trying to write zeros to them with dd.

From what I understand, when I attempt writing data directly to the bad sectors, it should trigger a reallocation, reducing current pending sectors by one and increasing the reallocated sector count.

However, on this disk both Reallocated_Sector_Ct and Reallocated_Event_Count raw values are 0, and dd fails with I/O errors when I attempt to write zeros to the bad sectors. dd works fine, however, when I write to a good sector.

# dd if=/dev/zero of=/dev/sdb bs=512 count=1 seek=217152
dd: error writing ‘/dev/sdb’: Input/output error

Does this mean that my drive, in some way, has no spare sectors to be used for reallocation? Is my drive just in general a terrible person? (The drive isn't actually mine, I'm helping a friend out. They might have just gotten a cheap drive or something.)

In case it is relevant, here is the output of smartctl -i :

Model Family:     Western Digital Caviar Green (AF)
Device Model:     WDC WD15EARS-00Z5B1
Serial Number:    WD-WMAVU3027748
LU WWN Device Id: 5 0014ee 25998d213
Firmware Version: 80.00A80
User Capacity:    1,500,301,910,016 bytes [1.50 TB]
Sector Size:      512 bytes logical/physical
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ATA8-ACS (minor revision not indicated)
SATA Version is:  SATA 2.6, 3.0 Gb/s
Local Time is:    Fri Oct 18 17:47:29 2013 CDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

UPDATE:
I have run shred on the disk, which has caused Current_Pending_Sector to go to zero. However, Reallocated_Sector_Ct and Reallocated_Event_Count are still zero, and dd is now able to write data to the sectors it was previously unable to. This leads me with several other questions:

• Why aren't the reallocations being recored by the disk? I'm assuming the reallocation took place as I can now write data directly to the sector and couldn't before.

• Why did shred cause reallocation and not dd? Does the fact that shred writes random data instead of just zeros make a difference?