Trouble making an Ubuntu flavour (dual-boot) USB stick with persistence file(s)

[Ralf Mardorf]

Hi,

I try to make an USB stick providing a dual-boot or multi-boot
containing Xubuntu 20.04 + something else, perhaps just Xubuntu 20.10,
all with persistence supported by a file.

I tried Ventoy, but I'm willing to test anything else, too.
Booting into a live user session works without issues, but persistence
doesn't work. Actually the Ventoy menu only shows one Xubuntu entry, no
persistence related entry at all.

At first I run

# ventoy -i -r 13615 -L v1.ventoy /dev/sdf

then I used gparted to reformat the exFAT partition to Ext4.

"you can reformat the 1st partition with other filesystem,
exFAT/FAT32/NTFS/UDF/XFS/Ext2/Ext3/Ext4 are supported"
- https://www.ventoy.net/en/doc_disk_layout.html

After that I wanted to add persistence by a file as described by
https://www.ventoy.net/en/plugin_persistence.html , taking into account
that "The persistent file/partition name in Ubuntu 20.04 has been
officially changed from  casper-rw  to  writable "
- https://askubuntu.com/questions/1236445/casper-rw-persistence-files-not-working-with-20-04
by running

# /opt/ventoy/CreatePersistentImg.sh -s 6400 -t ext4 -l writable
# mv -i persistence.dat xubuntu-20.04.1-desktop-pers1.dat

This is the used and probably faulty ventoy.json:

# cat /mnt/VTOYEFI/ventoy/ventoy.json 
{
    "persistence": [
        {
            "image": "xubuntu-20.04.1-desktop-amd64.iso",
            "backend": "xubuntu-20.04.1-desktop-pers1.dat"
        }
    ]
}





This is how the USB stick does look like:




# lsblk -o name,mountpoint,label,size,fstype /dev/sdf
NAME   MOUNTPOINT     LABEL      SIZE FSTYPE
sdf                             29.3G 
├─sdf1 /mnt/v1.ventoy v1.ventoy   16G ext4
├─sdf2 /mnt/VTOYEFI   VTOYEFI     32M vfat (fat16)
└─sdf3 /mnt/V1FAT32   V1FAT32   13.3G vfat (fat32)


# /usr/bin/ls -hAl /mnt/{V1FAT32,VTOYEFI,v1.ventoy}
/mnt/V1FAT32:
total 0

/mnt/VTOYEFI:
total 8.0K
drwxr-xr-x 3 root root 2.0K Dec 23 11:23 EFI
drwxr-xr-x 8 root root 2.0K Dec 23 11:23 grub
drwxr-xr-x 2 root root 2.0K Dec 23 11:23 tool
drwxr-xr-x 4 root root 2.0K Jan  5 07:07 ventoy

/mnt/v1.ventoy:
total 7.9G
-rw-r--r-- 1 root root 1.6G Jul 31 18:51 xubuntu-20.04.1-desktop-amd64.iso
-rw-r--r-- 1 root root 6.3G Jan  5 06:55 xubuntu-20.04.1-desktop-pers1.dat



I only edited /mnt/VTOYEFI/ventoy/ventoy.json all other directories or
files stay with the defaults. FWIW I didn't test  casper-rw . I suspect
another user error. Maybe a broken ventoy.json or missing to add/mount
the persistent file manually when running the live session or something
else.

Any hints are welcome!

Regards,
Ralf