persistent directory on usb drive

[Paul Merrell]

If you want write privileges, why install the DVD to the thumb drive?
Why not instead install the OS to the thumb drive? The only live
CD/DVD distros I've tried that enable writes to disk require that you
write to a hard drive or other medium rather than to the CD/DVD.
(Read-only is a limitation of the data storage media the live distros
are designed for.)

I think I understand what you want to do but do not understand why.

Nb., you will probably be dissatisfied with performance unless you are
using a USB 3.0 thumb drive via a USB 3.0 connector.

Best regards,

Paul