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Fujitsu: "ECC On the Fly Count”.
196. Reallocation Event Count
It is count of sectors reallocation. Value raw indicates total count of attempts, successful and
not successful.
Count of remap operations (transferring data from a bad sector to a special reserved disk area
- spare area). The raw value of this attribute shows the total number of attempts to transfer
data from reallocated sectors to a spare area. Unsuccessful attempts are counted as well as
successful.
Reallocation Event Count means drive found some weak sectors and marked them pending.
But later it was able to successfully recover these sectors (by reading or writing them).
Reallocation Event Count records both successful and unsuccessful tries.
A bad sector marked by the disk (and invisible to the operating system) can be counted as
"reallocation event" or "reallocated sector count". If these numbers start growing, something is
seriously wrong.
197. Current Pending Sector Count
Amount of pending sectors. If the sector issues and error during read or write the drive marks
it as pending for a certain time before replacing this error sector with a spare one.
Current count of unstable sectors (waiting for remapping). The raw value of this attribute
indicates the total number of sectors waiting for remapping. Later, when some of these sectors
are read successfully, the value is decreased. If errors still occur when reading some sector,
the hard drive will try to restore the data, transfer it to the reserved disk area (spare area) and
mark this sector as remapped. If this attribute value remains at zero, it indicates that the
quality of the corresponding surface area is low.
Those are sectors that couldn't be properly read and that the hard disk logic is waiting for a
write operation to try to remap to a spare sector (if available). A simple disk surface scan
won't be enough to force the remap operation. You need a read/write surface scan to remap
the sector. The best option should be a tool that knows about what should be read from that
sector so that it has some option to apply the best fix to the missing data.
The Current Pending Sector Count of one reflects a sector that has been marked as bad by the
operating system. I suspect that the drive's controller is aware that it is bad, but it cannot
relocate it until such time as the system writes to it, thereby signalling that the data in that
sector is no longer of any consequence.
It represents a sector that the drive has given up on, but not yet been able to replace, because
it was not written to it. The system does not factor into this.
198. Off-line Scan Uncorrectable Sector Count
Amount of error sectors detected during the last off-line scan. Count of uncorrectable
read/write sector errors. Growth of value row means worse condition of disk surface and/or
mechanical subsystem.
The Uncorrectable Errors Count attribute returns the number of uncorrectable ECC errors
(Error Correction Codes) that occurred. This counter increments if more than four bits in the
affected sector
are uncorrectable. The raw value of this attribute indicates the total number of uncorrectable
errors when reading/writing a sector. A rise in the value of this attribute indicates that there
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