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Date: Thu, 05 Mar 2009 20:03:45 +0100
From: Tobias Blersch <abitos@abitos.org>
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To: Oliver Fromme <olli@lurza.secnetix.de>
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Cc: freebsd-hackers@FreeBSD.ORG
Subject: Re: Spin down HDD after disk sync or before power off
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Oliver Fromme wrote:
>  > Joerg Sonnenberger wrote:
>  > This is not true. Many hard disks don't like having to do an emergency
>  > shutdown as it affects the disk life time negatively. That's what
>  > happens if you poweroff the machine when the disks are still spinning.
> 
> Can you point to any authoritative information (URL) about
> that claim, such as vendor specs, white paper or similar?

http://www.hitachigst.com/tech/techlib.nsf/techdocs/28DCCB17E0EEC5A086256F4E006E2F5B

Thats the specification for my notebooks hard drive. Section 6.6
Reliability gives data about how to power-off the disk. It also contains
numbers of supported load/unloads and emergency unloads. Emergency
unloads are invoked when the heads are still loaded and power fails.

> The product supports a minimum of 600,000 normal load/unloads.
> The drive supports a minimum of 20,000 emergency unloads.


Tobias