path: root/qemu-img.texi
diff options
authorKevin Wolf <kwolf@redhat.com>2011-01-17 15:35:28 +0100
committerKevin Wolf <kwolf@redhat.com>2011-01-24 16:41:49 +0100
commite61846908efd5ea0916d157a82adabf0674a01b0 (patch)
tree412c39fa90ae1063c7a15eea6f003f978e760956 /qemu-img.texi
parent1635eecc413ed680013cf77e6994901cafe15590 (diff)
Documentation: Add qemu-img check/rebase
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'qemu-img.texi')
1 files changed, 41 insertions, 0 deletions
diff --git a/qemu-img.texi b/qemu-img.texi
index 1b90ddbcfc..ced64a40ed 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -59,6 +59,13 @@ lists all snapshots in the given image
Command description:
@table @option
+@item check [-f @var{fmt}] @var{filename}
+Perform a consistency check on the disk image @var{filename}.
+Only the formats @code{qcow2}, @code{qed} and @code{vdi} support
+consistency checks.
@item create [-f @var{fmt}] [-o @var{options}] @var{filename} [@var{size}]
Create the new disk image @var{filename} of size @var{size} and format
@@ -107,6 +114,40 @@ they are displayed too.
List, apply, create or delete snapshots in image @var{filename}.
+@item rebase [-f @var{fmt}] [-u] -b @var{backing_file} [-F @var{backing_fmt}] @var{filename}
+Changes the backing file of an image. Only the formats @code{qcow2} and
+@code{qed} support changing the backing file.
+The backing file is changed to @var{backing_file} and (if the image format of
+@var{filename} supports this) the backing file format is changed to
+There are two different modes in which @code{rebase} can operate:
+@table @option
+@item Safe mode
+This is the default mode and performs a real rebase operation. The new backing
+file may differ from the old one and qemu-img rebase will take care of keeping
+the guest-visible content of @var{filename} unchanged.
+In order to achieve this, any clusters that differ between @var{backing_file}
+and the old backing file of @var{filename} are merged into @var{filename}
+before actually changing the backing file.
+Note that the safe mode is an expensive operation, comparable to converting
+an image. It only works if the old backing file still exists.
+@item Unsafe mode
+qemu-img uses the unsafe mode if @code{-u} is specified. In this mode, only the
+backing file name and format of @var{filename} is changed without any checks
+on the file contents. The user must take care of specifying the correct new
+backing file, or the guest-visible content of the image will be corrupted.
+This mode is useful for renaming or moving the backing file to somewhere else.
+It can be used without an accessible old backing file, i.e. you can use it to
+fix an image whose backing file has already been moved/renamed.
+@end table
@item resize @var{filename} [+ | -]@var{size}
Change the disk image as if it had been created with @var{size}.