Path or prefix of it is already a part of volume:

This occurs when you are trying to add a previously removed brick to the volume. You can clear this out as mentioned below :

setfattr -x trusted.glusterfs.volume-id /path/to/share

setfattr -x  trusted.gfid  /path/to/share

gluster failed to get the ‘volume file’ from server
This error occurs if you are trying to directly mount the gluster filesystem using the pathname. Try using the volume name and the problem should be resolved.