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understanding  "reallocated sector counts"

Posted on 2015-01-29
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HWinfo displays a field called [Reallocated Sector Count] 92/36, Worst: 92 (Data = 342)

Can someone help me interpret these readings?
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Question by:bga123
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David Johnson, CD, MVP earned 1500 total points
ID: 40578945
all new high capacity drives user error detection and correction within the drive itself. If a drive has problems with a sector it will relocate that sector to a spare sector.
It shows 36 sectors available and using 92 sectors .. I believe that the 36 is incorrect and not reading the SMART data properly or the manufacturer actually has more.   You should only worry if reallocated sectors is increasing consistently. If the number is constant after several boots, then it isn't a problem. If it increases consistently then you should be worried.
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by:bga123
ID: 40579029
Thanks you David. That was a clear explanation. Would you know what the Data=342 means? I tried CrystalDiskInfo and it confirmed the reading of 92/36
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by:bga123
ID: 40579034
For anyone who happens to stumble upon this question the following text comes from the wikipedia entry for 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.[3] 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. If sequential access speed is critical, the remapped sectors can be manually marked as bad blocks in the file system in order to prevent their use.
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by:garycase
ID: 40579238
"... It shows 36 sectors available and using 92 sectors .. "  ==> That's not at all what those numbers mean !!   SMART parameters are reported with a "value" that's set by the manufacturer based on a scale that ranges to either 100 or 200 for each parameter.  [Unfortunately this isn't standardized ... not only do different manufacturers use a different max, but even with the same manufacturer there will be some parameters that start at 100 and others at 200.    The important thing is that the values are above the thresholds ... and hopefully close to the max values.

The numbers you're seeing are 92 for the current value of this parameter, with a threshold of 36 -- the threshold is the value that will cause this parameter to fail the SMART test.    The data value (342) is the actual number of reallocated sectors you currently have.    That's a fairly high number, but I've seen higher ... and as David correctly noted, the most important thing to watch is whether or not it changes over time.
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