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From: Tijl Coosemans <tijl@ulyssis.org>
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Cc: octavian.covalschi@gmail.com, Alexander Motin <mav@freebsd.org>,
	Daniel Thiele <dthiele@gmx.net>
Subject: Re: Spin down HDD after disk sync or before power off
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On Thursday 05 March 2009 22:22:09 Daniel Thiele wrote:
> Looking at the numbers in the Hitachi drive specifications Tobias an I
> dug out from the Hitachi website (see replies in the Joerg Sonnenberger
> branch of this thread) the normal Load/Unload count is about 30 times
> higher than the Emergency Unload count. So even if an
> ATA_STANDBY_IMMEDIATE command may introduce additional Load/Unload
> stress on reboot it is not as bad as the stress causes by an Emergency
> Unload on shutdown. Of course this only applies if the "click" sound is
> really caused by an Emergency Unload. Is there a way to figure out?
> Maybe the S.M.A.R.T. feature records the two kinds of power-offs.

Emergency Unload is called Power-Off_Retract_Count in SMART output.