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Date:      Tue, 4 Mar 1997 10:31:57 +1030 (CST)
From:      Michael Smith <msmith@atrad.adelaide.edu.au>
To:        joerg_wunsch@uriah.heep.sax.de
Cc:        freebsd-hackers@FreeBSD.ORG
Subject:   Re: scsi spindown
Message-ID:  <199703040001.KAA08579@genesis.atrad.adelaide.edu.au>
In-Reply-To: <Mutt.19970303111741.j@uriah.heep.sax.de> from J Wunsch at "Mar 3, 97 11:17:41 am"

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J Wunsch stands accused of saying:
> As Michael Smith wrote:
> 
> > > Has anyone modified FreeBSD-anything to spindown scsi (direct) drives
> > > after some period of non-use?
> 
> > A lot of disks will refuse to spin down.
> 
> So you won't get this feature for these old suckers, what's the deal?

You will get lots of nasty error messages instead.

> >  Better to configure your disks
> > to spin themselves down using scsi(8) if they support it.
> 
> Where should this be supported?  IDE drives do sometimes support this
> (though the standard is very very funky for this), but SCSI?  I've
> never stumpled across a mode page setting that allows for an auto
> spindown.

Probably as vendor-dependant as for IDE disks.  You could also use a
cron job that read a sysctl variable to get the last time that a disk
was accessed and then spin it down using scsi(8).

> The `od' driver supports spindown while the device is being unused.
> Supporting spindown while the device is open will requires some
> restructuring of the code.

I don't know about the internals of the SCSI system wrt. sending the
spindown command, but I know the SCSI code is reasonably tolerant of
"please wait" messages from drives (from having powered them down and
up again while the system is on...).

> cheers, J"org


-- 
]] Mike Smith, Software Engineer        msmith@gsoft.com.au             [[
]] Genesis Software                     genesis@gsoft.com.au            [[
]] High-speed data acquisition and      (GSM mobile)     0411-222-496   [[
]] realtime instrument control.         (ph)          +61-8-8267-3493   [[
]] Unix hardware collector.             "Where are your PEZ?" The Tick  [[



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