Boot from External Storage - Can't create /fstab: Read-only file system

[jonty]

I'm trying to Boot from an External Storage USB Drive on my Omega2 running the latest firmware(v233).

When I try to generate the device’s fstab entry using block-mount:
block detect > /etc/config/fstab , I get the following error:

can't create /etc/config/fstab: Read-only file system

What could be the reason for this and is there a way to fix this?

[crispyoz]

@jonty clean up your file system to give yourself a little more space.