I applied the changes to my GL-MT300N-V2 as per the instructions on the [OpenWrt Wiki] Extroot configuration website and added a 32g usb stick.
It all seem to be okay and mango rebooted successfully.
Using df from root terminal I get sensible numbers
root@GL-MT300N-V2:~# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/root 12032 12032 0 100% /rom
tmpfs 60980 1544 59436 3% /tmp
/dev/sda1 30060388 1528 28506532 0% /overlay
overlayfs:/overlay 30060388 1528 28506532 0% /
tmpfs 512 0 512 0% /dev
/dev/mtdblock6 1664 764 900 46% /rwm
/dev/sda1 30060388 1528 28506532 0% /mnt/extra
the overlay is now on my usb stick and /rwm seems to be the old overlay partition.
/mnt/extra is also mu USB stick
So far all looks good but the status window flash memory space seems a bit confused
and it says 16.00 MB Total
System Used -173899.39%(0.00 B)
Apps Used9.33%(1.49 MB)
Available173990.06%(27.19 GB)
Current Firmware Version4.3.18
Not sure if this is just a display issue or something to be worried about.
Thanks
David