Questions[unionfs](ubuntu)

I am building a ubuntu 20.04 server using the raspberry pi image. one of the big weaknesses of the pi is that it is using an sd card as the main drive. This tends to lead to a dead device after a period of time due to the card failing due to writing.

Raspbian or pi os now includes an easy way - flicking a switch - to add a union fs - a writable layer over a read only layer - on the sd card. I believe they are using OverlayFS. I am wondering whether Ubuntu has the equivalent or if there are easy ways to implement. In my looking I have failed to find anything specific to the pi.

I have mounted a directory with the following command

sudo unionfs -o cow,max_files=32768 -o allow_other,use_ino,suid,dev,nonempty stuff-linux64=RW stuff

How do I change stuff-linux64 from RW to RO and add another directory (stuff-update64) on top?

The end result should look like I'd executed:

sudo unionfs -o cow,max_files=32768 -o allow_other,use_ino,suid,dev,nonempty stuff-update64=RW:stuff-linux64=RO stuff

after unmounting stuff.

For that matter, how do I unmount a filesystem that I mounted with unionfs?

I noticed today that Ubuntu 12.04 will not include aufs.

What, if anything, will be available to facilitate the creation of union mounts?

I configured aufs as a Root File System On Usb Flash Drive by this article. So the first brunch is real root FS and it is read-only. The second brunch FS is in memory and it is read-write capable. Both brunches combined in one file-based Copy-On-Write union and mounted at / .

All things seams working well, but network interface. While the Ubuntu 11.10 Oneric 3.0.0-16-server x86_64 booting I see next message: Waiting network configuration

After it boots eth0 don't bring UP:

rootubuntu:~# ifconfig
lo Link encap:Local Loopback
met addr:127.O.O.1 Mask:255.O.O.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACI< RUNNING MTU:16436 Metric:1
RX packets:0 errors:O dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:O overruns:O carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 6) TX bytes:0 (0.0 6)

restarting networking not helping:

root@ubuntu:~# /etc/init.d/networking restart
* Running /etc/init.d/networking restart is deprecated because it may not enabie again some interfaces
* Reconfiguring network interfaces...
dhclient3: error while loading shared libraries: libc.so.6: cannot open shared object file: No such file or directory
Failed to bring up ethO.

The library libc.so.6 remains the same place at /lib/x86_64-linux-gnu/libc-2.13.so and link /lib/x86_64-linux-gnu/libc.so.6 for it. When I boot normally (without aufs as root FS ) all things go well again.

How to FIX it?