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On a Mint 19 Mate pen drive persistent setup, I attempt to copy the casper-rw persistent file limited to 4GB to an ext4 partition.

I am looking for the steps to transfer applications and data to an xt4 casper-rw partition and boot it from the pendrive.

Steps so far:

I have created an ext4 partition named casper-rw

I copied all casper-rw files using rsync -r -p -o -E

I removed casper-rw from the pendrive.

I rebooted counting on the ext4 casper-rw partition getting priority over the casper-rw file. The ext4 casper-rw partition appeared as casper-rw but was accessed as /casper-rw1.

On reboot there was one "cow format specified as overlayfs and no support found" error.

A second reboot brought Mint back with the ext4 casper-rw partition now mounted as casper-rw while the casper-rw file partition was also accessible.

On the next reboot expecting to boot using the ext4 casper-rw partition, "cow overlaysfs" again.

Removing the casper-rw file or backtracking to a previous casper-rw saved file resulted in the same error.

casper-rw ext4 partition could not be renamed by Windows EaseUS Partition Master. Using SystemRescueCd iso loaded on YUBI I was able to use gparted to change the ext4 casper-rw partition name.

Now I am back up with the casper-rw file mounted.

What I can try to move forward?

casper package 1.394 ubiquity-casper 1.394 lupin-casper 0.57build1

  • Some persistent live systems work only with a casper-rw file, not a casper-rw partition. Try with mkusb: install mkusb and let it create a casper-rw partition (by default in the same drive as its system). Later on you can create another partition with an ext file system, give it the label casper-rw and rename or remove the original casper-rw partition (in the same drive as its system). You can also create a home-rw partition (with the label home-rw), which will store the modifications (files, tweaks etc.) of your home directory. – sudodus Nov 23 '18 at 8:08
  • Thanks. I put on the back burner the idea of booting from a pendrive with a casper-rw ext4 partition. The express purpose was avoiding writing onto either the SSD MBR or partition boot sector. The 4GB casper-rw file got gobled up by a 2.6GB /var/logs directory. The pendrive / disk partition solution is probably worth exploring further. I'd recommend a complete install to an external SSD for switching from another OS to Linux rather than trying to push the limits of the pendrive setup. – OneArb Nov 23 '18 at 17:54
  • I have good experiences of both installed linux systems (like installed into an internal drive) and persistent live linux systems in external SSD drives :-) – sudodus Nov 23 '18 at 18:12
  • @sudodus Probably worth trying another clean install. Which distro did you get the casper-rw ext4 partition to work? – OneArb Nov 23 '18 at 18:26
  • It works with mkusb and the Ubuntu family (standard Ubuntu and the community flavours), Debian, Linux Mint (and some other distros that are similar enough to them). Tell me the name of the iso file with Linux Mint that you are using, and I can test if it works. – sudodus Nov 23 '18 at 18:56
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I downloaded linuxmint-19-cinnamon-64bit.iso last July, and mkusb can make a persistent live drive from it. I tested right now (using the default settings) with a Sandisk Extreme 16 GB USB3 pendrive.

You can see in the screenshot that the data of the root partition is the same as the casper-rw partition according to df. This indicates that the persistence works.

enter image description here

It is possible to grab more of the available drive space for persistence. If you select 100%, there will be no usbdata partition with NTFS.

enter image description here

  • The use case remains to install applications and data on casper-rw file then create an ext4 casper-rw partition, transfer applications and data, finaly boot from the ext4 partition. – OneArb Nov 24 '18 at 13:54
  • mkusb creates a casper-rw partition directly. There will be no casper-rw file. So you need not transter anything unless you want a casper-rw partition in another drive (for example an internal drive). – sudodus Nov 24 '18 at 14:00
  • Thanks. When I get around to it, I will copying everything to ext4 casper-rw then in terminal try update-grub to see if it will generate a new menu option to boot into the casper-rw ext4 partition. If not I can try to update the grub package following steps in itsfoss.com/solve-error-partition-grub-rescue-ubuntu-linux – OneArb Nov 24 '18 at 14:19
  • There is an option in mkusb to backup the /home directory and to restore it to a new casper-rw partition. Do not copy the whole content of the current system's casper-rw file to a new casper-rw partition, because it will probably fail (the system will probably not work after that). This means that your personal files and tweaks (stored in /home) can be copied, but you must re-install installed program packages and global tweaks (if any). update-grub is made for installed systems, do not use it here (except for very special cases, when you know that it works). – sudodus Nov 24 '18 at 18:30
  • That's a great feature to know about. The use case is about moving from a liveCD to a usable production environment. This is a great step towards it. – OneArb Nov 26 '18 at 10:57

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