- It is not necessary to start booting with EFI if you have GPT partitions (you could choose to have legacy boot with GPT partitions).
- It is not necessary that EFI partition be at the start of a disk: it could be in every place, provided that it has a) boot (esp) flags, and b) at least 110mb of space.
System not starting after upgrading to Ubuntu 22.04
After upgrading Ubuntu from 20.04 to 22.04 it can happen that you cannot start the desktop: emergency mode.
In some case it could be happened that fstab was modified and the efi partition is set with a wrong UUID. Therefore you can try to change, in your fstab file, the efi UUID (i.g. copying it from a working installation).
ssd slow (in Linux)
If your SSD has become slow, it could depend from the swap file: f.e. in fstab the ssd swap UUID could be wrong (after some partitions changes in your SSD).
You can fix this by giving to the swap partition the correct UUID.
a non-destructive way to modify a multi-boot
You can try gdisk: a very simple, easy, fast and safe, command-line tool.
With gdisk you can make several actions, such as:
- convert a MBR disk to a GPT one (with the command gdsk and then the disk you want modify , i.g. /dev/sda, and the doing the command “w”, that is “write”)
- re-order your partition table (with the command “s”, that is “sort”), if in your disk there is some “desorder”, i.g. if /dev/sdb8 is before /dev/sdb6.
Be careful, if you get a warning message that partitions will be deleted: it can really happen.
But mainly be careful that if you change the order of SO partitions you could not be more able to boot.