vnc: Make ledstate comparison before modifiers updated

[qemu.git] / qemu-img.texi

diff --git a/qemu-img.texi b/qemu-img.texi
index 360543b807e6854d20f551f19cf4d971578f1d7c..69f1bda6aec0895572e82eac8250e8a97bd97574 100644 (file)
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -28,6 +28,10 @@ Command parameters:
 is the disk image format. It is guessed automatically in most cases. See below
 for a description of the supported disk formats.
 
 is the disk image format. It is guessed automatically in most cases. See below
 for a description of the supported disk formats.
 

+@item --backing-chain
+will enumerate information about backing files in a disk image chain. Refer
+below for further description.
+

 @item size
 is the disk image size in bytes. Optional suffixes @code{k} or @code{K}
 (kilobyte, 1024) @code{M} (megabyte, 1024k) and @code{G} (gigabyte, 1024M)
 @item size
 is the disk image size in bytes. Optional suffixes @code{k} or @code{K}
 (kilobyte, 1024) @code{M} (megabyte, 1024k) and @code{G} (gigabyte, 1024M)


@@ -50,6 +54,9 @@ indicates that target image must be compressed (qcow format only)
 with or without a command shows help and lists the supported formats
 @item -p
 display progress bar (convert and rebase commands only)
 with or without a command shows help and lists the supported formats
 @item -p
 display progress bar (convert and rebase commands only)

+@item -q
+Quiet mode - do not print any output (except errors). There's no progress bar
+in case both @var{-q} and @var{-p} options are used.

 @item -S @var{size}
 indicates the consecutive number of bytes that must contain only zeros
 for qemu-img to create a sparse image during conversion. This value is rounded
 @item -S @var{size}
 indicates the consecutive number of bytes that must contain only zeros
 for qemu-img to create a sparse image during conversion. This value is rounded


@@ -77,12 +84,25 @@ deletes a snapshot
 lists all snapshots in the given image
 @end table
 
 lists all snapshots in the given image
 @end table
 

+Parameters to compare subcommand:
+
+@table @option
+
+@item -f
+First image format
+@item -F
+Second image format
+@item -s
+Strict mode - fail on on different image size or sector allocation
+@end table
+

 Command description:
 
 @table @option
 Command description:
 
 @table @option

-@item check [-f @var{fmt}] [-r [leaks | all]] @var{filename}
+@item check [-f @var{fmt}] [--output=@var{ofmt}] [-r [leaks | all]] @var{filename}

 
 

-Perform a consistency check on the disk image @var{filename}.
+Perform a consistency check on the disk image @var{filename}. The command can
+output in the format @var{ofmt} which is either @code{human} or @code{json}.

 
 If @code{-r} is specified, qemu-img tries to repair any inconsistencies found
 during the check. @code{-r leaks} repairs only cluster leaks, whereas
 
 If @code{-r} is specified, qemu-img tries to repair any inconsistencies found
 during the check. @code{-r leaks} repairs only cluster leaks, whereas


@@ -110,6 +130,47 @@ it doesn't need to be specified separately in this case.
 
 Commit the changes recorded in @var{filename} in its base image.
 
 
 Commit the changes recorded in @var{filename} in its base image.
 

+@item compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-s] [-q] @var{filename1} @var{filename2}
+
+Check if two images have the same content. You can compare images with
+different format or settings.
+
+The format is probed unless you specify it by @var{-f} (used for
+@var{filename1}) and/or @var{-F} (used for @var{filename2}) option.
+
+By default, images with different size are considered identical if the larger
+image contains only unallocated and/or zeroed sectors in the area after the end
+of the other image. In addition, if any sector is not allocated in one image
+and contains only zero bytes in the second one, it is evaluated as equal. You
+can use Strict mode by specifying the @var{-s} option. When compare runs in
+Strict mode, it fails in case image size differs or a sector is allocated in
+one image and is not allocated in the second one.
+
+By default, compare prints out a result message. This message displays
+information that both images are same or the position of the first different
+byte. In addition, result message can report different image size in case
+Strict mode is used.
+
+Compare exits with @code{0} in case the images are equal and with @code{1}
+in case the images differ. Other exit codes mean an error occurred during
+execution and standard error output should contain an error message.
+The following table sumarizes all exit codes of the compare subcommand:
+
+@table @option
+
+@item 0
+Images are identical
+@item 1
+Images differ
+@item 2
+Error on opening an image
+@item 3
+Error on checking a sector allocation
+@item 4
+Error on reading data
+
+@end table
+

 @item convert [-c] [-p] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
 
 Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to disk image @var{output_filename}
 @item convert [-c] [-p] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
 
 Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to disk image @var{output_filename}


@@ -129,12 +190,28 @@ created as a copy on write image of the specified base image; the
 @var{backing_file} should have the same content as the input's base image,
 however the path, image format, etc may differ.
 
 @var{backing_file} should have the same content as the input's base image,
 however the path, image format, etc may differ.
 

-@item info [-f @var{fmt}] @var{filename}
+@item info [-f @var{fmt}] [--output=@var{ofmt}] [--backing-chain] @var{filename}

 
 Give information about the disk image @var{filename}. Use it in
 particular to know the size reserved on disk which can be different
 from the displayed size. If VM snapshots are stored in the disk image,
 
 Give information about the disk image @var{filename}. Use it in
 particular to know the size reserved on disk which can be different
 from the displayed size. If VM snapshots are stored in the disk image,

-they are displayed too.
+they are displayed too. The command can output in the format @var{ofmt}
+which is either @code{human} or @code{json}.
+
+If a disk image has a backing file chain, information about each disk image in
+the chain can be recursively enumerated by using the option @code{--backing-chain}.
+
+For instance, if you have an image chain like:
+
+@example
+base.qcow2 <- snap1.qcow2 <- snap2.qcow2
+@end example
+
+To enumerate information about each disk image in the above chain, starting from top to base, do:
+
+@example
+qemu-img info --backing-chain snap2.qcow2
+@end example

 
 @item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename}
 
 
 @item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename}
 


@@ -147,7 +224,9 @@ Changes the backing file of an image. Only the formats @code{qcow2} and
 
 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
 
 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}.
+@var{backing_fmt}. If @var{backing_file} is specified as ``'' (the empty
+string), then the image is rebased onto no backing file (i.e. it will exist
+independently of any backing file).

 
 There are two different modes in which @code{rebase} can operate:
 @table @option
 
 There are two different modes in which @code{rebase} can operate:
 @table @option


@@ -204,7 +283,10 @@ After using this command to grow a disk image, you must use file system and
 partitioning tools inside the VM to actually begin using the new space on the
 device.
 @end table
 partitioning tools inside the VM to actually begin using the new space on the
 device.
 @end table

+@c man end

 
 

+@ignore
+@c man begin NOTES

 Supported image file formats:
 
 @table @option
 Supported image file formats:
 
 @table @option


@@ -225,6 +307,13 @@ support of multiple VM snapshots.
 
 Supported options:
 @table @code
 
 Supported options:
 @table @code

+@item compat
+Determines the qcow2 version to use. @code{compat=0.10} uses the traditional
+image format that can be read by any QEMU since 0.10 (this is the default).
+@code{compat=1.1} enables image format extensions that only QEMU 1.1 and
+newer understand. Amongst others, this includes zero clusters, which allow
+efficient copy-on-read for sparse images.
+

 @item backing_file
 File name of a base image (see @option{create} subcommand)
 @item backing_fmt
 @item backing_file
 File name of a base image (see @option{create} subcommand)
 @item backing_fmt


@@ -245,73 +334,33 @@ Preallocation mode (allowed values: off, metadata). An image with preallocated
 metadata is initially larger but can improve performance when the image needs
 to grow.
 
 metadata is initially larger but can improve performance when the image needs
 to grow.
 

-@end table
-
-@item qed
-Image format with support for backing files and compact image files (when your
-filesystem or transport medium does not support holes).  Good performance due
-to less metadata than the more featureful qcow2 format, especially with
-cache=writethrough or cache=directsync.  Consider using qcow2 which will soon
-have a similar optimization and is most actively developed.
-
-Supported options:
-@table @code
-@item backing_file
-File name of a base image (see @option{create} subcommand).
-@item backing_fmt
-Image file format of backing file (optional).  Useful if the format cannot be
-autodetected because it has no header, like some vhd/vpc files.
-@item cluster_size
-Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller
-cluster sizes can improve the image file size whereas larger cluster sizes
-generally provide better performance.
-@item table_size
-Changes the number of clusters per L1/L2 table (must be power-of-2 between 1
-and 16).  There is normally no need to change this value but this option can be
-used for performance benchmarking.
-@end table
-
-@item qcow
-Old QEMU image format. Left for compatibility.
-
-Supported options:
-@table @code
-@item backing_file
-File name of a base image (see @option{create} subcommand)
-@item encryption
-If this option is set to @code{on}, the image is encrypted.
-@end table
+@item lazy_refcounts
+If this option is set to @code{on}, reference count updates are postponed with
+the goal of avoiding metadata I/O and improving performance. This is
+particularly interesting with @option{cache=writethrough} which doesn't batch
+metadata updates. The tradeoff is that after a host crash, the reference count
+tables must be rebuilt, i.e. on the next open an (automatic) @code{qemu-img
+check -r all} is required, which may take some time.

 
 

-@item cow
-User Mode Linux Copy On Write image format. Used to be the only growable
-image format in QEMU. It is supported only for compatibility with
-previous versions. It does not work on win32.
-@item vdi
-VirtualBox 1.1 compatible image format.
-@item vmdk
-VMware 3 and 4 compatible image format.
+This option can only be enabled if @code{compat=1.1} is specified.

 
 

-Supported options:
-@table @code
-@item backing_fmt
-Image format of the base image
-@item compat6
-Create a VMDK version 6 image (instead of version 4)

 @end table
 
 @end table
 

-@item vpc
-VirtualPC compatible image format (VHD).
+@item Other
+QEMU also supports various other image file formats for compatibility with
+older QEMU versions or other hypervisors, including VMDK, VDI, VHD (vpc), qcow1
+and QED. For a full list of supported formats see @code{qemu-img --help}.
+For a more detailed description of these formats, see the QEMU Emulation User
+Documentation.

 
 

-@item cloop
-Linux Compressed Loop image, useful only to reuse directly compressed
-CD-ROM images present for example in the Knoppix CD-ROMs.
+The main purpose of the block drivers for these formats is image conversion.
+For running VMs, it is recommended to convert the disk images to either raw or
+qcow2 in order to achieve good performance.

 @end table
 
 
 @c man end
 
 @end table
 
 
 @c man end
 

-@ignore
-

 @setfilename qemu-img
 @settitle QEMU disk image utility
 
 @setfilename qemu-img
 @settitle QEMU disk image utility