[Question] Differences of the read and write mode?

Hi,

one can set the mode of a zarr array to be read or write (amongst other modes). What are the different effects of such modes?
In particular, if I create a larger-than-RAM array in write-only mode, does it mean that no memory will be occupied by the array?
If yes, is this also true if I write into different chunks in this write-only array?

Best,
Karol