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From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: Alexander Motin <mav@FreeBSD.org>
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	<4B570B4C.9000203@jrv.org> <4B69817B.8090706@FreeBSD.org>
Date: Fri, 05 Mar 2010 13:18:03 +0100
In-Reply-To: <4B69817B.8090706@FreeBSD.org> (Alexander Motin's message of
	"Wed, 03 Feb 2010 16:00:27 +0200")
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Cc: FreeBSD-Current <freebsd-current@freebsd.org>,
	"James R. Van Artsdalen" <james-freebsd-current@jrv.org>
Subject: Re: Pack of CAM improvements
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Alexander Motin <mav@FreeBSD.org> writes:
> I've just added Power Up In Stand-by (PUIS) feature support into CAM
> ATA in HEAD.  It is one of the ways to implement staggered spin-up for
> ATA devices.  Now CAM will spin-up no more then 4 of such devices at a
> time.

Hmm, how does that work?  Doesn't the BIOS spin the disks up long before
the kernel even loads?  Can you set a flag on the disk to tell it not
to?

This is a very real issue for me.  I have a file server that can't cold
boot because the disks take too long to spin up and / or the PSU can't
deliver enough power to spin them all up at the same time.  I would love
to be able to delay spinning up each disk until it's actually needed
(i.e. /etc/rc.d/zfs start).

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no