path: root/Documentation
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authorDavid Sterba <>2016-03-15 17:16:00 +0100
committerDavid Sterba <>2016-03-15 17:16:00 +0100
commit7aedf5067b7596ba351a02a03f0fb5e434f69389 (patch)
tree344573339fe1603e0244027f74f35cfe343defe9 /Documentation
parent029b2433eb37f275718fe55d819a46244d738eaf (diff)
btrfs-progs: docs: update dump-super
Signed-off-by: David Sterba <>
Diffstat (limited to 'Documentation')
1 files changed, 17 insertions, 22 deletions
diff --git a/Documentation/btrfs-inspect-internal.asciidoc b/Documentation/btrfs-inspect-internal.asciidoc
index fae6ed6f..62d42bce 100644
--- a/Documentation/btrfs-inspect-internal.asciidoc
+++ b/Documentation/btrfs-inspect-internal.asciidoc
@@ -20,37 +20,32 @@ requires calls to privileged ioctls.
*dump-super* [options] <device> [device...]::
-(needs root privileges)
-Show btrfs superblock information stored in devices.
-It is used to print the information of superblock,
-you can specify which mirror to print out.
+(replaces the standalone tool *btrfs-show-super*)
-By default, every device's first superblock will be printed out.
+Show btrfs superblock information stored on given devices in textual form.
+By default the first superblock is printed, more details about all copies or
+additional backup data can be printed.
-Mainly used for debug purpose.
+Besides verifictaion of the filesystem signature, there are no other sanity
+checks. The superblock checksum status is reported, the device item and
+filesystem UUIDs are checked and reported.
-Print full superblock information.
-Including the system chunk array and backup roots.
-Print information of all superblocks.
+print full superblock information, including the system chunk array and backup roots
+print information about all present superblock copies (cannot be used together with '-i' option)
+-i <super_mirror>::::
+specify which mirror to print, valid values are 0, 1 and 2 and the superblock must be present on the device
-If this option is given, '-i' option will be ignored.
+If there are multiple options specified, only the last one is applies.
--i <super_mirror>::::
-Specify which mirror to print out.
+attempt to print the superblock even if thre's no valid BTRFS signature found
-<super_mirror> is between 0 and 2.
-If several '-i <super_mirror>' are given, only the last one is valid.
+The result may be completely wrong if the data do not resemble a superblock.
-Attempt to print the superblock even if no superblock magic is found. May end
-s <bytenr>::::
specify offset to a superblock in a non-standard location at 'bytenr', useful
for debugging (disables the '-f' option)