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Cc: Alexander Motin <mav@FreeBSD.org>,
	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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On 2010-03-05 13:18, Dag-Erling Sm=C3=B8rgrav wrote:
> Hmm, how does that work?  Doesn't the BIOS spin the disks up long befor=
e
> the kernel even loads?  Can you set a flag on the disk to tell it not
> to?

A jumper (marked PM2 on WD disks; no idea for other brands).  From
Wikipedia:

"[PUIS] can usually be enabled by a jumper shunt on the drive but can be
configured by other means (configuration sector) using manufacturer
specific tools."

and:

"PUIS requires corresponding BIOS support. If [PUIS] is enabled on the
drive but not supported by the BIOS, the drive will not be detected by
the system or detected as zero in size. PUIS typically only supported on
RAID Controllers."

I have an Areca RAID card that indeed has this capability.  It can also
spin up the disks in staggered fashion, with a selectable interval.