About making single layer DVD backups of Mac OS X


Hello, I've read several guides and made several backups myself but I still can't figure out:

• what makes or doesn't make a Mac OS X DVD bootable ?
• in which cases should the back-up DVD appear when restarting with the alt key ?
• which are the models of Macs that can't read burned single layer DVDs (DVD-R SL) ?


1. a properly burned copy of a bootable DVD will be bootable, assuming that the Mac is compatible with that OS X version.
2. the only way that a disk will appear in the Option-boot screen, is if it is both bootable, and is a version that will boot that particular Mac.
For example, a bootable 10.4 DVD will not appear in the Option-boot screen on a recent Intel Mac, but would appear on that same screen on a PPC Mac that supports that version.

3. All Mac models that have DVD-ROMs will read single-layer DVDs - at least they SHOULD, assuming that the DVD drive is working properly.
I would say that all Macs sold new over the last 10 years will read DVDs, which would include single-layer (or dual-layer, for that matter - all DVD-ROMs also have the capability of reading dual-layer DVDs. Not all can BURN dual-layer DVDs, which needs a burner with that capability)

Are you having a specific problem? Can you give some details about that?


Are you having a specific problem? Can you give some details about that?
example 1: the DVD would not boot but it showed up when pressing alt and gives a kernel panic, the Mac was too recent - this is against what you said about alt

example 2: the DVD mounts but doesn't boot on 2 Macs until an external DVD drive is used


Both of your examples still point to a bad DVD, or a faulty/dirty DVD drive, or attempting to boot with an incompatible OS X version.
I did ask for more details, which you haven't provided yet.

Here's some examples of details that will be more "helpful":
What version of OS X are you trying to boot from? Be sure to include the "point" (OS X 10.4.6; OS X 10.6.3; etc)
Which model Mac are you trying to boot? Specific model would be great (not just "MacBook"). The System Identifier from the System Information/Profiler would be perfect.
Also, any other hardware and software information that you wish to supply, such as RAM installed; if you have other copies of your installer DVDs that work better, etc.

If your Macs won't boot from the internal drive, but will boot from an external drive - then it makes sense that both Macs have problems with the internal drive.
Keep in mind that mounting a disk does not necessarily mean that the system will boot from that disk, or that the disk is even bootable.
If you can boot from that same DVD simply by using an external DVD drive, then there must be some problem with the internal DVD drive.

Finally, I've had innumerable times that a DVD disk may not boot, even though everything else seems to be OK. I have often "restored" the bootable installer DVD to an external hard drive partition that I created just for that purpose. Even better, is to copy the DVD (using Disk Utility/Restore) to a USB flash drive. This is assuming that your Macs are Intel models, and not the older PPCs - which don't kindly boot to USB devices.
So, which Macs do you have - and what OS X version are you trying to install? Don't forget provide as much detail as you think I might need.

One more thing - I can mount a 10.8.2 installer on my 2008 MacBook.
It shows as a choice in Startup Disk, and also shows as a choice in the Option-boot screen. However (even though it appears to be bootable) - I cannot boot to that installer - my MacBook is too old, and it crashes when I try to boot to that Mountain Lion installer.
That's why I need more details....
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