The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.
The mounted root file system is a snapshot (named
install
) of the root file system taken at the
end of installation. To find out the ID of the parent of the
root file system subvolume, use the following command:
# btrfs subvolume list /
ID 258 top level 5 path install
In this example, the installation root file system subvolume has
an ID of 5. The subvolume with ID 258
(install
) is currently mounted as
/
. Figure 20.1, “Layout of the root File System Following Installation”
illustrates the layout of the file system:
The top-level subvolume with ID 5 records the contents of the
root file system file system at the end of installation. The
default subvolume (install
) with ID 258 is
currently mounted as the active root file system.
The mount command shows the device that is currently mounted as the root file system:
# mount
/dev/mapper/vg_btrfs-lv_root on / type btrfs (rw)
...
To mount the installation root file system volume, you can use the following commands:
#mkdir /instroot
#mount -o subvolid=5 /dev/mapper/vg_btrfs-lv_root /instroot
If you list the contents of /instroot
, you
can see both the contents of the installation root file system
volume and the install
snapshot, for example:
# ls /instroot
bin cgroup etc install lib64 misc net proc sbin srv tmp var
boot dev home lib media mnt opt root selinux sys usr
The contents of /
and
/instroot/install
are identical as
demonstrated in the following example where a file
(foo
) created in
/instroot/install
is also visible in
/
:
#touch /instroot/install/foo
#ls /
bin cgroup etc home lib media mnt opt root selinux sys usr boot dev foo instroot lib64 misc net proc sbin srv tmp var #ls /instroot/install
bin cgroup etc home lib media mnt opt root selinux sys usr boot dev foo instroot lib64 misc net proc sbin srv tmp var #rm -f /foo
#ls /
bin cgroup etc instroot lib64 misc net proc sbin srv tmp var boot dev home lib media mnt opt root selinux sys usr #ls /instroot/install
bin cgroup etc instroot lib64 misc net proc sbin srv tmp var boot dev home lib media mnt opt root selinux sys usr