Re: More than 4 gigs of memory (Bootable Ubuntu)
A live/install iso on bootable USB is a FAT32 file system which is limited to maximum file size of just under 4 GB. But a casper-rw file is a loop mounted ext2 file system, so the size of the casper-rw file does not reflect how much data is on the loop mounted file. So just because casper-rw is about 4 GB does not mean that it is full or that you cannot delete files from it to make room for other files.
There is supposed to be a way to have the live/install iso automatically use a separate partition with a casper-rw label, but I have not figured out how to do that. Then as an ext2 or whatever partition, the persistent data could be any size.
But really that is insecure, since anyone who boots it can get into Linux without a password with root access to anything. So it would be better to have large enough flash (8 GB minimum recommended) to do a regular install instead of using the live/install iso. That would also allow you to use proprietary video drivers and do kernel updates, etc. that you cannot do with the live/install iso (without remastering your own iso), because the live/install iso initially boots from a fixed squashfs file system before persistent data is mounted.
i5 650 3.2 GHz, 8 GB, nvidia GTX 1060, 32" 1080p & assorted older computers