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| -rw-r--r-- | qemu-img.texi | 41 |
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 +@var{backing_fmt}. + +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}. |