I am not familiar with the specific properties of glusterfs. I hope for the input of others.
If the files you want to store are mostly office, PDF, jpg/png/… files, then I don’t see any particular reason why you should suffer a hefty performance penalty. This said, it is probably not the highest performing setup though.
Have a look at this thread: GlusterFS as local storage target for Seafile-data This may be interesting for you.