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pxeboot/netboot (including diskless netboot)

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I originally posted on this topic in a reply in the Netbook section here, but it is really more general than that so I thought I would post follow-ups here. I will not reproduce all of the information that is there, so I would suggest looking at that post for the basics.


This concerns booting a given machine completely over the network: what Apple normally calls diskless netboot (there is also netboot where the operating system is loaded from th network, but

a local disk is used for some storage related to making the network image appear writable). I will try to distinguish between the two where it is significant. An example of such a machine is illustrated in this screen shot (which is a better one than in the original post; the original post was not "diskless netboot" as described above as at that time I had not figured out to make it work at all):




Note that the boot volume shows as a network disk image (at least that is Apple's icon for such) and that the disk in this machine actually only shows  Windows partitions (it is a Dell D630 running Windows 10 normally, but the partitions are mounted via NTFS-3G).


I described the bare essential details in the earlier post so will not repeat them here unless needed to provide context to answer questions.


Since that post I have learned some things and made some progress. The most important was enabling diskless netboot, albeit in a very limited and restricted sense.The limitation is at the moment I can

only handle one diskless machine of this type booted at a time from the server. I do know what it would take to make it work more generally, but have not yet found code sufficiently close to what I need to hack it up fairly easily. In the meantime I've implemented it by making some changes to the /etc/rc.netboot script in the disk image (this will be required in either case), although it is modified in sucha way that if the information is available through normal channels, it will work in that way preferentially, but, if not, it will fall back to this single-client only mode. Note that I have not implemented a way to actually police this so it is most likely "gentlemen's timesharing" as we used to say, although it may actually fail for the second person as he tries to gain write access to the shadow file that is already in use.


I should mention my motivation for this project. I do some small amount of consulting for a shop that is mostly a mac shop but is gaining some Windoze clients, mostly machines from fairly naive users that are very poor at maintenance. Sometimes I need to access files but either can't boot windows on the machine, or need to do things with respect to moving files around that windows doesn't want to allow even an administrator to do, so I like to be able to access the disk with some system other than windows. Since it's a customer's machine, I can't really install OS X, which I tend to prefer as I am more familiar with it on a day-to-day basis and am less likely to mess something up. Otherwise, what I want to do could mostly be accomplished with Ubuntu Live (which I also have netboot set up for on my server, which is a quad G5 (powerpc) mac running 10.5.8 server. Note that the fact that I am using a real mac for the server is largely a convenience for me; it is not required that the server be running OS X or anything in particular as long as the correct services needed are able to be provided by the system.


Now it would also be possible to (maybe) boot off an external disk, but that is often more problematic than one would like (keeping track of which disks can boot which machines, finding the disks, etc. I woudl much prefer to have nicely named server repositories to handle the varying hardware. This varied hardware, sadly is what made me realize that my ideal will be pretty impossible to attain. However, I do have a system whcih can be used in at least some cases (with a minor tweak during boot time, I can boot the Dell or a Lenovo G550 to varying degress of success). Note that I don't necessarily expect all the fine details to work, either, although that is not necessarily a problem with only netboots, again, due to the varied hardware.


So, what doesn't work for me now (at least in Snow Leopard, which is what I've been using for various reasons). Main thing right now is I can't upgrade netboot to 10.6.8. I have been able to upgrade the Lenovo on disk to 10.6.8, so it does run on that machine, but somehow the BCM7522 driver (the Adlan driver) doesn't seem to handle the network traffic as well and drops off-line (never to reterun)

during the netboot, which is  fatal, of 10.6.8. I've also try the BCDM5906 driver on the machine that has that chip, but it has the same issues.


Of course, the netboot only works at best as well as a disk-based system would. In this case that means the screen doesn't work on the dell (but VNC to the machine does), and the native resolution of the G550 doesn't work.  I'm not sure whyt 10.6.8 is so much worse on this than 10.6.3 which at least in this particular aspect, seems to work fine.

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