GELI encryption and HDD critical temperature

[cpghost]

On Tue, Feb 19, 2008 at 11:41:18AM +0300, s.g. wrote:
> According to smartctl -a, the temperature of the encrypted drives is ~59C. 
> The temperature of the unencrypted drive is, however,  ~41C, according to 
> the same smartctl -a.

The CPU has to work extra hard to encrypt/decrypt, and it is possible
that the extra heat this generates is absorbed by the HDDs. But since
the only drive that's overheating is the encrypted one, it seems to be
something else.

> Am I right assuming  GELI encryption is the reason for such a "global 
> warming"?

I don't know. But I've noticed that when drives access GBDE-encrypted
partitions (I didn't try with GELI yet), they are much louder (head
seeking). It seems they seek more often on encrypted than non-encrypted
partitions. Perhaps caching is turned off at some point up the chain?
If that's the case, it is no wonder that encrypted partitions tend to
result in higher drive temps (and faster drive wear).

Is there a way to measure the number of head seeks in near real-time
to confirm or disprove this?

> Grigorian

-cpghost.

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