Rescue Media
Two extra partitions hold a full Arch ISO on local disk, so recovery doesn't depend on having a USB drive on hand.
The disk layout reserves two dedicated partitions by default: about 5.5GB total (512MB FAT32 + 5GB ext4), on top of whatever your root filesystem needs. Opt out of both together if you're tight on disk space:
- A small FAT32 partition holding the extracted kernel and initramfs.
- A larger ext4 partition holding the fetched Arch ISO itself, as a plain file.
The split exists because the bootloader (Limine) can't read ext4 and has no GRUB-style loopback command, and FAT32 has a hard 4GB per-file cap that the ISO itself would run into. During install, this is fetched from an official mirror, checksum-verified, and wired into a permanent boot menu entry, the same mechanism the official Arch installation media itself uses to loop-mount an ISO file at boot.
The stored ISO is refreshed manually only, never automatically. A background download on every boot or update would be surprising and wasteful, and a slightly outdated rescue ISO is still far better than none at all.
This is what snapshot rollback's live-ISO mode uses when there's no other way to boot the machine.