What I want – A flashdrive that can boot multiple versions of Ubuntu, (from iso files), each with it's own persistent partition.
What I don't want – A flashdrive with a persistent file limited to 4GB, or a multibooter with only one persistent partition.
Home-rw files or partitions don't count, Full installs don't count.
I want to be able to update by dragging and dropping new Ubuntu iso's onto the drive.
The keyword here is MultiPersistence, I could not find the answer in Google or in previous posts.
UPDATE
Sundar Ima, gives a hint at a solution in MultiBootUSB V8, adding "persistent-path=/(folderx)/" after "persistent" in the grub2 menuentry.
This allows the use of multiple casper-rw files on the same disk.
For example:
menuentry "ubuntu1.iso" {
set root=(hd0,1)
loopback loop /isos/ubuntu1.iso
linux (loop)/casper/vmlinuz.efi boot=casper persistent persistent-path=/casper1/ iso-scan/filename=/isos/ubuntu1.iso noeject noprompt --
initrd (loop)/casper/initrd.lz
}
menuentry "ubuntu2.iso" {
set root=(hd0,1)
loopback loop /isos/ubuntu2.iso
linux (loop)/casper/vmlinuz.efi boot=casper persistent persistent-path=/casper2/ iso-scan/filename=/isos/ubuntu2.iso noeject noprompt --
initrd (loop)/casper/initrd.lz
}
The first menuentry boots an iso named "ubuntu1.iso" located in the folder named "isos" using the casper-rw file located in the folder named "casper1".
The second menuentry boots an iso named "ubuntu2.iso" located in the folder named "isos" using the casper-rw file located in the folder named "casper2".
The problem is that the size of the casper-rw files is still limited to 4GB. ( I will try AlexatUnuntu's solution just in case things have changed in the past few years).
Having a limited understanding of grub2, I think the solution to multiple persistent partitions is to use "persistent-path=" to point to the desired casper-rw partition for each iso's menuentry, but how?
Best Answer
The maximum work space for persistence is 8 GiB (not 4 GiB). The casper-rw file is maximum 4 GiB and the home-rw file is also maximum 4 GB. But there are restrictions, max 4 GiB for the system (installed programs) and max 4 GiB for tweaks and personal files.
It is possible to have an extra data partition for huge files like video clips, so maybe these 8 GiB will be enough for many users, who want multibooting with persistence for more than one of the systems.
This works with a FAT32 file system and with adding
after "persistent" in the grub2 menuentry for each iso file to get separate storage for persistence in a multiboot pendrive.