Blinker said:
Is the notebook hard drive Anti-Shock protection really important
feature (does it park the heads automatically?), or its mostly
manufacturer's trick, and this protection is essentially useless? Some
notebooks have this feature, some not. If the laptop has no the HDD
anti-shock protection, is this serious drawback, or its not very important?
You can go to a hard drive manufacturer web site, and download
the available data, to get some numbers.
For example, if the drive is running, it can take up to 350G's
of single impulse shock. If the head is unloaded, that number may
increase to 1000G's, an improvement of a factor of 3.
Drives are also sensitive to vibration, which is repetitive motion.
Say you clamped the laptop in a paint shaker machine at the
paint store - that would be an example of large amplitude vibration.
The hard drive can take less of that. When the laptop hits the floor,
some of the energy could be in the form of vibrations. A drop to
the floor is not a simple single impulse shock.
Another question is "what makes the G's ?". Back when I took
Physics 100, the professor did a nice demonstration. He drops
a large steel ball onto a steel plate. The measurement equipment
said the G force was somewhere between 1000 G's and 10000 G's
(I don't remember the exact number now). The important thing
about the demo, is that it takes "rigid" materials, in order
for one object to be brought to rest so quickly, as to
experience a high G number. Laptops may not be quite that
rigid, which means it is more difficult, for the drop to the
floor to achieve a high single impulse G force. Just like the
"crumple zone" in your car, the body of the laptop increases
the time it takes for the laptop to come to rest. So "soft" materials
provide some measure of protection. If the laptop, or the floor
for that matter, were large steel plates, things might be a
bit different.
That leaves vibration as a more likely source of damage. Since the
laptop striking the floor is not a "simple" impact, the analysis of
what actually causes the damage is more difficult.
On the one hand, the simple math says the hard drive is now protected
three times better, if the laptop manages to make a response before
impact. The question remains though, as to whether that is sufficient
to prevent you from losing data in all circumstances or not.
What we don't know, is how the physics of each laptop, compares
to the shock and vibration specs of 2.5" hard drives.
A good way to protect yourself in any case, is daily backups to
an external hard drive. That, more than anything, covers you
against all sorts of events - such as theft...
If you want another way of making the drive more shock resistant,
buy an SSD drive replacement. Some laptop makers offer this as
a build option.
*******
The best SSD you can buy...
http://download.intel.com/design/flash/nand/extreme/319984.pdf
"Shock - Operating and Non-operating: 1,000G/0.5msec
Vibration - Operating: 2.17 GRMS (7-800 Hz)
- Non-operating 3.13 GRMS (10-500 Hz)"
*******
We can compare that to a Seagate hard drive.
http://www.seagate.com/staticfiles/...tebook/momentus/5400.6 (Wyatt)/100528359d.pdf
"Shock, operating (Gs max at 2 msec) 350
Shock, nonoperating (Gs max at 2 msec) 800
Shock, nonoperating (Gs max at 1 msec) 1,000
Shock, nonoperating (Gs max at 0.5 msec) 600
Vibration, operating 1.0 G (0 to peak, 5–500 Hz)
Vibration, nonoperating 5.0 Gs (0 to peak, 5–500 Hz)"
******
The advantage of the SSD, is its resistance to upset is
the same whether running or not. The question then, is whether
the resistance to upset is sufficient to protect you every
time the laptop is dropped.
If I read further into the specification of that Seagate drive,
the "Free Fall" detection feature, is inside the hard drive itself.
The laptop plays a part, by setting the register in the hard
drive controller, to enable the feature.
"2.13.1 Free Fall Protection feature
The Free Fall Protection feature provides enhanced data protection
against shock events that may occur while the drive is operating.
This feature is designed to decrease the likelihood of data loss
by detecting a free fall event and unloading the actuator before a
shock takes place in falls of >8 inches (nominal). The drive uses a
zero G sensor mounted on the printed circuit board assembly (PCBA)
to sense this event.
To enable the Free Fall Protection feature on the models, use
Set Features command 41h. To disable this feature, use Set Features
command C1h. Information about Free Fall Events that have occurred
is available through SMART attribute FEh.
Note. Of the models documented in this product manual, the Free Fall
Protection feature is provided only on ST9500325ASG, ST9320325ASG,
ST9250315ASG, ST9160314ASG, ST9120315ASG, and ST980313ASG models."
If the BIOS has the appropriate controls, you may be able to retrofit
a Free Fall drive at a later date. At least, as long as the control
mechanism is the same on all brands.
HTH,
Paul
