ZyXEL Communications NAS540, User Manual

Page: 81 / 372

Chapter 8 Storage Manager
Cloud Storage User’s Guide
81
8.4 iSCSI
The NAS supports the iSCSI (Internet Small Computer System Interface) standard and can serve as
an iSCSI target. When the iSCSI initiator is successfully connected to an iSCSI target over an IP
204 Soft ECC
Correction
Low This is the number of errors corrected by software ECC (Error Correction
Code).
205 Thermal Asperity
Rate (TAR)
Low This is the number of thermal asperity errors. Thermal asperity is a read
signal spike caused by sensor temperature rise due to touching the disk
surface or contaminant particles.
206 Flying Height This is the height of the hard drive’s read/write heads above the disk
surface.
207 Spin High
Current
This is the quantity of high current used to spin up the drive.
208 Spin Buzz This is the number of buzz routines to spin up the drive. When the arm
holding the read/write heads is stuck, the motor driving it tries to oscillate
the arm to free it. This causes an audible vibration.
209 Offline Seek
Performance
This is the hard drive’s seek performance during offline operations. Offline
operations are tests the drive does itself as opposed to those that an
external diagnostic tool has it do. Seek performance is how quickly the
drive moves from track to track.
220 Disk Shift Low This is how far the disk has moved relative to the spindle (this kind of
shift is usually due to shock).
221 G-Sense Error
Rate
Low This is the number of errors that have resulted from external vibration
and shock.
222 Loaded Hours This is how long the hard drive has operated under data load (this
requires movement of the magnetic head armature).
223 Load/Unload
Retry Count
This is how many time the magnetic head has changed position.
224 Load Friction Low This is resistance caused by friction in mechanical parts during operation.
225 Load/Unload
Cycle Count
Low This is the total number of load cycles.
226 Load 'In'-time This is the total time that the magnetic heads actuator has had a load
(not been in the parking area).
227 Torque
Amplification
Count
Low This is the number of attempts to compensate for variations in platter
speed.
228 Power-Off
Retract Cycle
Low This is how many times the magnetic armature was automatically
retracted because the power was cut.
230 GMR Head
Amplitude
This is the amplitude of thrashing (or the distance of repetitive forward
and reverse head motion).
231 Temperature Low This is the hard drive’s temperature.
240 Head Flying
Hours
This is the total time that the head has been positioning.
250 Read Error Retry
Rate
Low This is the number of errors in reading from the disk.
Table 21
S.M.A.R.T. Attributes (continued)
ID
ATTRIBUTE
NAME
BETTER DESCRIPTION