No, you’re meant to burn the ISO itself. Last time I needed to burn a disc on my Mac (which has been a while ago), I used Burn:
https://burn-osx.sourceforge.io/Pages/English/home.html
I don’t have way to connect the DVD to another Mac quickly but it will boot the mini. I have an install disk for Snow Leopard (10.6.3) and that boots up into the installer as you’d expect.
So, DVD player works and the mini will boot from it.
@danb35, so the DVD should contain the iso, just as if I’d copied it to another folder?
No, the ISO is an Image of the linux file system. The “contents” of the DVD must be burned, including bootstrap and whatever…
See this:
Andy
You missed the backup part, dude 
Hi
Not really! This dude has a well running backup system with ChronoSync (See Post 16). That’s a good tool… 
Otherwise:
Always better to have a backup too many, than one too little!
Immer besser, einen Backup zuviel zu haben, als genau eins zuwenig!
My 2 cents
Andy
So the instructions in the link you gave @Andy_Wismer are pretty much the exact same as on the page I found. I’ll have another attempt after lunch, but I do only have 10 DVDs and three are already in the bin…
Anyway, the one successful DVD has the actual iso ‘file’ and that’s all. Its not expanded the iso to a dmg, I don’t see the bootstrap. But if I use FInder to open the iso it becomes a volume on my Desktop called PVE and containing the bootstrap etc.
So if I need the contents of the iso and not just the iso, whatever is burning the disk isn’t making the contents - the PVE - available.
Does that make sense?
The contents is correct, but you just can’t copy over what you see in Finder. That won’t work as some of this stuff is per se invisible on a Mac, and the boot sector is important, not only on a HD, but also on CD/DVD.
It does, and it indicates that you burned the disc incorrectly. I gave a link up-thread to Burn, which will do what you need done. Andy gave you a link to a page showing three different ways to do this without any third-party software.
1 Like
And again…
OK, downloaded Burn and the result is a DVD with a copy of the iso. In other words, same result as burning via Finder.
I have four DVDs in the bin.
So maybe @Andy_Wismer means I need to open the iso and see the contents of “PVE”. And those files need to be burned. So I drag the files inside PVE to the Burn window? Or I drag PVE to the Burn window. And somehow all the hidden files will come along too. I think that suggests I drag PVE to Burn. Maybe. Possibly.
In my defence @danb35, I did follow the same instructions (albeit from a different webpage) that Andy gave me. Use Finder, drag the iso to the DVD and burn. Disk Utility (option two) isn’t possible on a 10.11 system. I admit I didn’t try the final, Terminal, option.
Hi
As it seems, the console method described is dependent on HDutil, so will only work pre 10.11…
I also at the moment have no ISO lying around… I just tried on my Macbook (forgetting to plug in my USB Superdrive…
Hm, no Burn option? Plugged in the Superdrive, Burn is shown.
Try DanBs burn app…
Those weren’t the instructions. The instructions were, “click on .iso, go to File menu, select burn Disk Image (filename) to disk”.
No, absolutely not. In no way, shape, or form do you mount the disc image on your Mac and then burn from there.
This is also official:
https://discussions.apple.com/thread/250786206
Burning on Mojave or Catalina from Console…
If you are not afraid of the command line, you can burn ISO images from there where the Finder fails. For example, to burn the latest Ubuntu ISO, load Terminal.app, and there you would type the command (in bold; the resulting output is below):
hdiutil burn ubuntu-19.10-desktop-amd64.iso
Please insert a disc:
Preparing data for burn
Opening session
Opening track
Writing track
…
Closing track
…
Closing session
…
Finishing burn
Verifying burn…
Verifying
…
Burn completed successfully
…
hdiutil: burn: completed
But the Finder method works:
Mark ISO Image in Finder
Go to files menu, at bottom select “burn Disk Image (filename) to disk”
Anything else besides a good program like the good old Toast Titanium (Toaster) just wastes a good DVD… 
I have three DVDs left. The last two failed to burn in Burn.
“This disk can’t be burned; it might be incompatible with this disc drive. Please try a different brand of disc or try burning at a slower speed.”
I had this a couple of times when burning using Finder too. Burning at 2x speed.
And failed to burn again. (Finder method.) Two discs left. Any ideas?
Do you have any other box with a burner?
Earlier I burned a disc using Burn.app by dragging the iso to the Burn.app window. Then, as I said
I can’t boot the Mac from that DVD. The DVD contains one file, a copy (as far as I know) of the iso.
What exactly should I see when I burn the iso to the DVD?
Moot point as I only have a single DVD left as either this is a dud batch or my SuperDrive is on its way out.
Yes, and earlier mini with a drive dated 2006. No idea if its CD or DVD!
Check that one out, but burn at a slow rate.
Or grab an older 5x Version of Proxmox, if I recall correctly, that fits on a CD. 5x can be updated to 6…
If you need a 5x image, i ought to still have one around…
The older CD/DVD isn’t an option as it has a different connector.