[Ukfreebsd] "green" HDDs

Tim Borgeaud tim at syntheticmoon.co.uk
Tue Jan 11 13:15:26 GMT 2011


Despite the fact that green credentials of these drives may be 
questionable, I think that in typical usage there are some definite benefits.

As far as I can tell, the performance of the somewhat slower spinning 
(5400 rpm) drives is not really that terrible at all. I believe that the 
slower spinning drives compare poorly in terms of random access, but 
overall there isn't a huge difference (at least not between similarly 
priced drives).

I suspect that the very aggressive power management features won't make 
any significant difference other than giving the drive a particular set of 
statistics with which it can be compared to others. However, I also 
suspect that in the vast majority of cases, drives will be idle for 
virtually the entire time that the host computer is turned on. I, 
therefore, think that any additional power and strain caused by waking 
from any power saving state is likely to be negligible.

Where the drives may have some advantage is where is it useful to keep the 
overall power of a system low. This may be for battery powered devices or 
it may be to allow a compact or very quiet computer. It's probably also 
worth noting that it is often the case that the slower spinning drives are 
also slightly quieter than the faster drives.

I also suspect that there may actually be some small benefit in power 
savings when considering large quantities of such drives in situations 
where the idle power of systems is relatively low (where a watt or two per 
drive might actually make a difference).

Tim


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