Free space for ubuntu live usb

[editheraven]

I've created a partition on my usb drive, with persistent file enabled. My question is : do I need free space on my root partition for further app install, or they are installed in persistent file?

[ajgreeny]

Everything goes into the persistence file of your live system, but if you really need a lot of space (more than 4GB) you can use a separate partition.
Details at http://ubuntuforums.org/showthread.php?t=2165496

[sudodus]

You can also consider making a normal installed system (but installed in a USB drive). This has the advantage of being more stable and it is possible to update the kernel, which is not possible in a persistent live system).