The GlusterFS documentation mentions how to set volume options, but there’s no obvious way to unset them. In the case that you’ve set something like
performance.cache-size and you just want to return to the defaults, you need to reset the setting:
[root@storage1 ~]# gluster volume reset homes performance.cache-size reset volume successful
Hopefully some SEO-fu will take place and this will help some other confused GlusterFS admins figure this out.