Pack of CAM improvements

Dag-Erling Smørgrav des at des.no
Fri Mar 5 12:18:05 UTC 2010


Alexander Motin <mav at 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
-- 
Dag-Erling Smørgrav - des at des.no


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