What does reallocated sectors mean?

[ontariotech]

Using Crystal Disk Info on a Hitachi 320Gb there is a yellow warning mark
after "reallocated sectors" - there are about 100 in total what does this mean?

[labtech]

See S.M.A.R.T in Wikipedia

[loki]

http://en.wikipedia.org/wiki/S.M.A.R.T.


"Count of reallocated sectors. When the hard drive finds a read/write/verification error, it marks that sector as "reallocated" and transfers data to a special reserved area (spare area). This process is also known as remapping, and reallocated sectors are called "remaps". The raw value normally represents a count of the bad sectors that have been found and remapped. Thus, the higher the attribute value, the more sectors the drive has had to reallocate. This allows a drive with bad sectors to continue operation; however, a drive which has had any reallocations at all is significantly more likely to fail in the near future.[2] While primarily used as a metric of the life expectancy of the drive, this number also affects performance. As the count of reallocated sectors increases, the read/write speed tends to become worse because the drive head is forced to seek to the reserved area whenever a remap is accessed. A workaround which will preserve drive speed at the expense of capacity is to create a disk partition over the region which contains remaps and instruct the operating system to not use that partition."