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Date:      Fri, 09 Oct 1998 09:42:19 +0930 (CST)
From:      "Daniel O'Connor" <doconnor@gsoft.com.au>
To:        "David E. Cross" <crossd@void.cs.rpi.edu>
Cc:        freebsd-current@FreeBSD.ORG, toasty@home.dragondata.com, Marius.Bendiksen@scancall.no, Mike Smith <mike@smith.net.au>, Terry Lambert <tlambert@primenet.com>
Subject:   Re: CDROM as system disk
Message-ID:  <XFMail.981009094219.doconnor@gsoft.com.au>
In-Reply-To: <Pine.SGI.4.04.9810081555490.1189-100000@void.cs.rpi.edu>

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On 08-Oct-98 David E. Cross wrote:
> > > Many drives don't offer any standard way of disabling the spindown; 
> > > you're basically stuck with it.
> > I thought you could avoid spindown by reading the thing...  >^).
>  Slight problem, disk caching. If you are going to ping the drive every N
>  time units as a 'keep-alive', those blocks will very quickly get cached;
>  unless you devise some clever algorithm that will always ensure that you
>  get a block not in the cache (consider the cache could me a megabyte or
>  more in size, and this gets tricky)
Err.. pick a random block and read it?
OK, not terribly good for the health of the drive, but neither is keeping
the drive spinning 100% of the time...

---------------------------------------------------------------------
|Daniel O'Connor software and network engineer for Genesis Software |
|http://www.gsoft.com.au                                            |
|The nice thing about standards is that there are so many of them to|
|choose from. -- Andrew Tanenbaum                                   |
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