Chapter 5 Storage Manager
NAS Series User’s Guide
78
5.3.3.3 S.M.A.R.T Attributes
The following table describes some common S.M.A.R.T. attributes. If a higher or lower raw attribute value
is better, it is indicated in the BETTER column. Since S.M.A.R.T. attributes and their definitions vary by
manufacturer, refer to the hard drive manufacturer for details about the attributes your hard drive
supports.
Updated This indicates when the hard drive updates the value for this attribute.
• Always means the hard drive updates this attribute during normal operation and during
offline activities.
• Offline means the hard drive only updates this attribute when no one is accessing the hard
drive.
When Failed This column indicates when (if ever) the attribute failed. An attribute has failed if the normalized
value is less than or equal to the threshold.
• -: This displays if the attribute is not failing now and has never failed in the past.
• FAILING_NOW: This displays if the attribute’s current normalized value is less than or equal to
the threshold.
• In_the_past: This displays if the attribute’s current normalized value is greater than the
threshold but the worst recorded value is less than or equal to the threshold.
Raw Data This is the attribute’s unprocessed raw data. These values show exact amounts of time or
numbers of attempts or errors. The meaning to the raw values is specific to the hard drive
manufacturer. Table 42 on page 156 has some information about whether a higher or lower
individual raw S.M.A.R.T. attribute value is better.
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Table 35 S.M.A.R.T Info
LABEL DESCRIPTION
Table 36 S.M.A.R.T. Attributes
ID
ATTRIBUTE
NAME
BETTER DESCRIPTION
01 Read Error Rate Low Shows the rate of hardware read errors. If this is not zero, there is a problem
with the disk surface or the read/write heads.
02 Throughput
Performance
High This is the hard drive’s general (overall) throughput performance. A
decreasing value indicates a problem.
03 Spin-Up Time Low This is the average number of milliseconds the hard drive took for spindle spin
up (from zero RPM to fully operational).
04 Start/Stop Count The total number of spindle start and stop cycles.
05 Reallocated
Sectors Count
Low Total number of reallocated sectors on the hard drive. When the hard drive
detects a read/write/verification error, it marks the sector as “reallocated”
and transfers the data to a specially reserved (spare) area. The process is
also known as remapping with “reallocated” sectors known as remaps. The
more sectors the hard drive has to reallocate, the slower read and write
speeds become.
06 Read Channel
Margin
This is the margin of a channel when it reads data.
07 Seek Error Rate Low This is the rate of the magnetic heads’ seek errors. A failure in the mechanical
positioning system, such as servo damage or a thermal widening of the disk,
results in seek errors. An increasing number of seek errors indicate the
condition of the disk surface and the mechanical subsystem are worsening.
08 Seek Time
Performance
High This is an average performance indicator for the seek operations of the
magnetic heads. Mechanical subsystem problems cause this value to
decrease.
09 Power-On Hours
(POH)
Low This is how many hours the hard drive has been in a power-on state. The raw
value lists the total number of hours (or minutes, or seconds depending on
the manufacturer).
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