Archived from groups: comp.sys.ibm.pc.hardware.storage (
More info?)
Previously mutefan@yahoo.com wrote:
> Hey, David (and Arno),
> Thanks LOADS. I just have some questions.
> 1) You're saying I have to avoid like the plague any external HD that
> does not come in an aluminum (or heat-dissipating) enclosure. Are
> enclosures usually included in the package, or are they another
> "peripheral" you have to add on to the cost of the HD?
Enclosures are included. However I found that an aluminium enclosure
without a fan is not enough for a 3.5" HDD when under load. I have
one that gets warm enough that it is uncomfortable to touch after
copying from/to it for half an hour. For 2.5" hdds the ratio of surface
to energy comsumption is far, far better.
> 2) If a geek such as I has no objections to hauling around a ton of
> bricks in a carrying case, IS there anything wrong with buying a heavy
> old external HD? There's a 60 GB Maxtor on sale at one of the sites I
> visited (I know, I know, you said to avoid Maxtor), but the sales rep
> said the major reason it was on sale was the weight.
Yes, it will die fast except if used lightly.
> 3) I'm a bit confused as to your (Arno vs. David, that is)
> disagreement on the 2.5/3.5 advantages. Are the 3.5 usually cheaper
> because they're bigger?
2.5" is optimised for notebook use. That means small, very low
energy consumption, more tolerant to heat and shock and can tolerate
far mor start/stop cycles (500.000 vs. 50.000). 3.5" is optimised for
capacity and speed. Most current 3.5" drives need solid mounting and
airflow to stay cool enough to life long. 2.5" disks usually do
not have airflow and they are optimised for low-power anyways.
To give you some concrete numbers: A 3.5" disk during R/W operation
consumes about 10-15W during R/W and seek operations (i.e. constant
access), while a 2.5" disk is more in the 2-2.5W range. Now if you
take an 3.5" aluminium casing and scale it down to 2.5" (approximated
as a spere), you get a resuction in surface by a factor of 2.7,
while the energy conumpion is lower by a factor of 5 (all rough
approximations and the reduction in heat dissipation of the 2.5"
case is likely significanlty less than 2.7), which gives you
half the temperature increase in the 2.5" drive that you see in
the 3.5" one.
Example: A 3.5" drive that heats up to 70C in 25C air (have seen that
and measured it) will correspond to a 2.5" at 50C. 50C is still in
acceptable limits. 70C is 15C above maximum and will have the drive
dying fast. Add to that thet the 2.5" drives I checked have a maximum
rated temperature of 60C while the 3.5" drives have 55C.
Again, if you plan on only light use (e.g. no longer accesses and
overall 1% disk access), you will be fine with an aluminium enclosure
and a 3.5" drive in it. Also if you have massive airflow, a
3.5" drive is fine for heavy use.
>> Note: The larger 5.25" ME-320 enclosures (loud fan) however are
>> recommended because they do have enough room and fast fan to cool any
>> 3.5" HD. But noisy vs. the aluminum model I recommend above, so I'd
>> pick that one.
> I'm a little stumped here. I could care less if the HD sounds like a
> sandblaster! Does the size of the enclosure matter? (Yeah, I know,
> probably a REALLY dumb question, but as I always say, If this group
> were moderated, then stupid people like me wouldn't be allowed to
> post...) I mean, if I get a big enclosure, can I fit EITHER a 2.5 or a
> 3.5 in it?
Only a good idea with significant airflow. You would have to use an
adapter for the mounting and the IDE connection. Whether the
2.5"+adapter fits, is another question.
Arno
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