--On Sat, 7 Sep 2002 20:08:05 -0400 Bernie Zenis <bzenis@mac.com> wrote: What do you mean by disk? The OS has to be read from something and it doesn't have to be a "disk" in the traditional sense of the word. Hard disk, CD, DVD, ZIP, etc. Not that a CD is write protected, and you can boot from it. I've heard of netbooting but I don't know any details. The outlines for this was described in another email, that is more or less how it works with darwin too (with darwin the kernel and the drivers are tftp-ed too, by the boot loader). Is nothing loaded from a local disk? Not necessarily, only if you set it up to do that. That is, does firmware make a network connection and download the needed files? Yes, OpenFirmware knows how to do this. Does a netbooted machine still need a local writable disk? Not necessarily, but see the swap issues below. Can VM work over a network? Probably, not sure, but that could be slow. (With a good server and gig ethernet you maybe could get pretty good performance though.) Does Darwin need to have swap file(s)? No, but many unix programs aren't really good on handling the case when there is no more memory to allocate, so you wouldn't want to do this for a general purpose user machine. (Mac OS 9 apps are usually better on handling that since it was something that happened every now and then.) This is not a problem with the kernel as much as with the applications that you may want to run, and probably also the libraries that they use. If RAM is large enough, can everything happen over the network? Certainly, but see above. For a general purpose machine, you will eat up all your RAM sooner or later, and things will probably start to fail. If the "disk" that contains the OS image and more importantly the VM swap space goes away the system will most likely fail soon afterwards. That is the answer I was expecting. I just want to know how robust or fail-safe Darwin is. I haven't tried it, but if you boot of a firewire disk and disconnects it, I wouldn't be surprised if you got something telling you to reconnect the disk so that the machine can continue doing things. If it has been allowed to swap things out it will probably need some of those pages again sometimes later. I think even parts of the kernel can be swapped out now adays. I'm mostly seeking knowledge. If Darwin can startup and run without a disk, then the whole Mac OS is closer to being able to do the same, Note that it can boot from a CD. The Mac OS X installer is running under Mac OS X. Check out the new Mac OS X Server Netboot stuff, I am not sure if they are swapping localy or not, you can probably set it up either way. then it might be useful to write Mac software that is "diskless friendly". I don't know what you mean by that, but it is never correct to assume that all disk accesses will work or that you can write everywhere you are used to, there can be hardware or permission problems for example. I guess a better, more general question might be, "Can Darwin startup and run without a writable disk, local or remote?" Yes, CD or NFS for example. Does any of this make sense to you or just to me? I don't really understand what you want to know. There is a spectrum of boot options, but they are not all recommendable for all kinds of use. A diskess Mac OS X lab room computer would probably be pretty useless if it couldn't swap, a darwin based ATM machine maybe wouldn't. Note that you need some kind of filesystem somewhere to get to the software to run. Otherwise you will only have a kernel with some drivers which isn't all that interresting (for most of us at least, maybe on this list there are people that actually have use for that :-). /ragge _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.