I have been playing around with a VM trying to install Gentoo, and it seems there are two options for my Master Boot Record : DOS and Solaris.
What is the difference? Which should I choose, or are there situations which I would prefer one over the other?
I believe the difference is that DOS uses the IBM Standard Master Boot Record format defined by IBM back in the early 80’s (and is the reason for the 2TB max-disk size we have), and Solaris uses the newer EFI standard. IIRC, Apple also uses EFI-style partitioning. Windows Dynamic Disks use EFI as well.
DOS-format has by far the most support from commodity PC motherboard BIOS. EFI is a better standard, in that it is more future proof, but adoption isn’t that great yet. There are two problems with the old DOS format; one is the 2TB max volume size I mentioned already, and the second is that some operating systems have a maximum partition count. That number is 16 or higher in most cases, so most folk should never run into it.
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