Re: Can Darwin Live Without Disks?
Re: Can Darwin Live Without Disks?
- Subject: Re: Can Darwin Live Without Disks?
- From: Emiel Kollof <email@hidden>
- Date: Mon, 9 Sep 2002 02:02:43 +0200
* Bernie Zenis (email@hidden) wrote:
>
>
I've heard of netbooting but I don't know any details. Is nothing loaded
>
from a local disk? That is, does firmware make a network connection and
>
download the needed files? Does a netbooted machine still need a local
>
writable disk? Can VM work over a network? Does Darwin need to have swap
>
file(s)? If RAM is large enough, can everything happen over the network?
Netbooting a UNIX usually depends on a BOOTP/DHCP/RARP to get an ip
number (which protocol is used depends on the hardware). Open Firmware
on newer (New world) macs is pretty content with DHCP. Then with tftp a
boot image is downloaded. This boot image contains something that
understands some remote file system like perhaps Appletalk or NFS. NFS
is more common. The boot image in turn fetched the kernel from that
network filesystem and boots it.
Usually there are these approches (assuming NFS):
1. The kernel knows NFS and can use a NFS root right away, and boots on.
2. A ramdisk is set up with a barebones root and boots on.
Swapping over NFS is quite common, but not recommended. Disks are slow,
but networks are usually slower.
The way Mac OS X/Darwin works is probably along those lines. So yes, in
theory it could function without a disk, given enough tinkering.
Hope that cleared stuff up a bit.
Cheers,
Emiel
--
Electricity is actually made up of extremely tiny particles, called
electrons, that you cannot see with the naked eye unless you have been
drinking. Electrons travel at the speed of light, which in most American
homes is 110 volts per hour. This is very fast. In the time it has taken
you to read this sentence so far, an electron could have traveled all the
way from San Francisco to Hackensack, New Jersey, although God alone knows
why it would want to.
The five main kinds of electricity are alternating current, direct current,
lightning, static, and European. Most American homes have alternating
current, which means that the electricity goes in one direction for a while,
then goes in the other direction. This prevents harmful electron buildup in
the wires.
-- Dave Barry, "The Taming of the Screw"
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