GoKawiilMaking Debian or Fedora persistent live images
Latest update: 2026-05-31 19:51:45
When you download a 'live' ISO, dd it to a USB drive, you notice that all your tweaks or installed packages vanish after a reboot. If you think about how most such 'live' ISOs work, it becomes apparent why:
$ parted -s Fedora-Xfce-Live-44-1.7.x86_64.iso print free | grep '^[PN ]' Partition Table: gpt Number Start End Size File system Name Flags 1 32.8kB 2897MB 2897MB ISO9660 hidden, msftdata 2 2897MB 2929MB 31.5MB fat16 Appended2 boot, esp 2929MB 2929MB 512B Free Space
ISO9660 is a read-only filesystem, & the fact it was written onto a writable medium is irrelevant: its fs driver contains no implementation for writing data blocks, & the Linux VFS layer immediately returns EROFS (code 30, Read-only file system) when it sees that a fs was mounted read-only.
A common workaround is to use OverlayFS; in the case of 'live' ISOs, to do an overlay with a chunk of RAM.
Obviously, you can do an overlay with a filesystem that supports write operations instead, like ext4, but inside the Live ISO there isn't one, & hence there is nothing to do an overlay with.
While you can always create an ext4 partition manually, how do you tell the 'live' OS to use it during boot? This distro corner has no standardisation whatsoever, & everybody is doing it in their own unique way. E.g., Debian & Ubuntu have diverged so much throughout the years that even the kernel parameters for their 'persistence' implementations differ. While it may seem logical to an impartial spectator to keep at least the user-facing interface the same between the distros, it's not how it is done in practice.
Ubuntu
Kernel parameter: "persistent".
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