What: /sys/fs/aufs/si_<id>/ Date: March 2009 Contact: J. R. Okajima <hooanon05g@gmail.com> Description: Under /sys/fs/aufs, a directory named si_<id> is created per aufs mount, where <id> is a unique id generated internally. What: /sys/fs/aufs/si_<id>/br0, br1 ... brN Date: March 2009 Contact: J. R. Okajima <hooanon05g@gmail.com> Description: It shows the abolute path of a member directory (which is called branch) in aufs, and its permission. What: /sys/fs/aufs/si_<id>/brid0, brid1 ... bridN Date: July 2013 Contact: J. R. Okajima <hooanon05g@gmail.com> Description: It shows the id of a member directory (which is called branch) in aufs. What: /sys/fs/aufs/si_<id>/xi_path Date: March 2009 Contact: J. R. Okajima <hooanon05g@gmail.com> Description: It shows the abolute path of XINO (External Inode Number Bitmap, Translation Table and Generation Table) file even if it is the default path. When the aufs mount option 'noxino' is specified, it will be empty. About XINO files, see the aufs manual.