ZyXEL Communications NSA-2401 User Manual
Chapter 6 Storage Screens
NSA-2401 User’s Guide
156
6.9.8 RAID and Data Protection
If a hard disk fails and you’re using a RAID 1, RAID 10, or RAID 5 array then your data will
still be available (but at degraded speeds until you replace the hard disk that failed and re-
synchronize the array). However, RAID cannot protect against file corruption, virus attacks,
files incorrectly deleted or modified, or the NSA malfunctioning. See
still be available (but at degraded speeds until you replace the hard disk that failed and re-
synchronize the array). However, RAID cannot protect against file corruption, virus attacks,
files incorrectly deleted or modified, or the NSA malfunctioning. See
for what you should use in these cases to protect data on your NSA.
6.9.9 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.
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.
Table 42 S.M.A.R.T. Attributes
ID
ATTRIBUTE
NAME
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.
a problem with the disk surface or the read/write heads.
02
Throughput
Performance
Performance
High
This is the hard drive’s general (overall) throughput performance.
A decreasing value indicates a problem.
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).
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
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.
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
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.
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
Performance
High
This is an average performance indicator for the seek operations
of the magnetic heads. Mechanical subsystem problems cause
this value to decrease.
of the magnetic heads. Mechanical subsystem problems cause
this value to decrease.
09
Power-On Hours
(POH)
(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).
state. The raw value lists the total number of hours (or minutes, or
seconds depending on the manufacturer).
10
Spin Retry Count Low
This is the total number of spin start retry attempts. This is the
number of attempts to spin up to fully operational speed the hard
drive has made when the first attempt did not succeed. An
increase in this value is an indicator of hard disk mechanical
subsystem problems.
number of attempts to spin up to fully operational speed the hard
drive has made when the first attempt did not succeed. An
increase in this value is an indicator of hard disk mechanical
subsystem problems.
11
Recalibration
Retries
Retries
High
This is the number of times recalibration was requested when the
first attempt did not succeed. A decrease in this value is an
indicator of hard disk mechanical subsystem problems.
first attempt did not succeed. A decrease in this value is an
indicator of hard disk mechanical subsystem problems.