5 virt-sparsify - Make a virtual machine disk sparse
9 virt-sparsify [--options] indisk outdisk
13 Virt-sparsify is a tool which can make a virtual machine disk (or any
14 disk image) sparse a.k.a. thin-provisioned. This means that free
15 space within the disk image can be converted back to free space on the
18 Virt-sparsify can locate and sparsify free space in most filesystems
19 (eg. ext2/3/4, btrfs, NTFS, etc.), and also in LVM physical volumes.
21 Virt-sparsify can also convert between some disk formats, for example
22 converting a raw disk image to a thin-provisioned qcow2 image.
24 Virt-sparsify can operate on any disk image, not just ones from
25 virtual machines. If a virtual machine has more than one attached
26 disk, you must sparsify each one separately.
28 =head2 IMPORTANT LIMITATIONS
34 Virt-sparsify does not do in-place modifications. It copies from a
35 source image to a destination image, leaving the source unchanged.
36 I<Check that the sparsification was successful before deleting the
41 The virtual machine I<must be shut down> before using this tool.
45 Virt-sparsify may require up to 2x the virtual size of the source disk
46 image (1 temporary copy + 1 destination image). This is in the worst
47 case and usually much less space is required.
51 Virt-sparsify cannot resize disk images. To do that, use
56 Virt-sparsify cannot handle encrypted disks.
60 Virt-sparsify cannot yet sparsify the space between partitions. Note
61 that this space is often used for critical items like bootloaders so
62 it's not really unused.
66 Virt-sparsify does not yet know how to sparsify swapspace. It is not
67 safe to do this unless we can be sure there is no hibernation data, so
68 at the moment swap partitions are ignored.
72 You may also want to read the manual pages for the associated tools
73 L<virt-filesystems(1)> and L<virt-df(1)> before starting.
79 virt-sparsify indisk outdisk
81 which copies C<indisk> to C<outdisk>, making the output sparse.
82 C<outdisk> is created, or overwritten if it already exists. The
83 format of the input disk is detected (eg. qcow2) and the same format
84 is used for the output disk.
86 To convert between formats, use the I<--convert> option:
88 virt-sparsify disk.raw --convert qcow2 disk.qcow2
90 Virt-sparsify tries to zero and sparsify free space on every
91 filesystem it can find within the source disk image. You can get it
92 to ignore (don't zero free space on) certain filesystems by doing:
94 virt-sparsify --ignore /dev/sda1 indisk outdisk
96 See L<virt-filesystems(1)> to get a list of filesystems within a disk
107 =item B<--convert> raw
109 =item B<--convert> qcow2
111 =item B<--convert> [other formats]
113 Use C<output-format> as the format for the destination image. If this
114 is not specified, then the input format is used.
116 Supported and known-working output formats are: C<raw>, C<qcow2>, C<vdi>.
118 You can also use any format supported by the L<qemu-img(1)> program,
119 eg. C<vmdk>, but support for other formats is reliant on qemu.
121 Specifying the I<--convert> option is usually a good idea, because
122 then virt-sparsify doesn't need to try to guess the input format.
126 Debug garbage collection and memory allocation. This is only useful
127 when debugging memory problems in virt-sparsify or the OCaml libguestfs
130 =item B<--format> raw
132 =item B<--format> qcow2
134 Specify the format of the input disk image. If this flag is not
135 given then it is auto-detected from the image itself.
137 If working with untrusted raw-format guest disk images, you should
138 ensure the format is always specified.
140 =item B<--ignore> filesystem
142 =item B<--ignore> volgroup
144 Ignore the named filesystem. Free space on the filesystem will not be
145 zeroed, but existing blocks of zeroes will still be sparsified.
147 In the second form, this ignores the named volume group. Use the
148 volume group name without the C</dev/> prefix, eg. I<--ignore vg_foo>
150 You can give this option multiple times.
152 =item B<--machine-readable>
154 This option is used to make the output more machine friendly
155 when being parsed by other programs. See
156 L</MACHINE READABLE OUTPUT> below.
162 This disables progress bars and other unnecessary output.
168 Enable verbose messages for debugging.
174 Display version number and exit.
178 Enable tracing of libguestfs API calls.
182 =head1 MACHINE READABLE OUTPUT
184 The I<--machine-readable> option can be used to make the output more
185 machine friendly, which is useful when calling virt-sparsify from
186 other programs, GUIs etc.
188 There are two ways to use this option.
190 Firstly use the option on its own to query the capabilities of the
191 virt-sparsify binary. Typical output looks like this:
193 $ virt-sparsify --machine-readable
198 A list of features is printed, one per line, and the program exits
201 Secondly use the option in conjunction with other options to make the
202 regular program output more machine friendly.
204 At the moment this means:
210 Progress bar messages can be parsed from stdout by looking for this
217 The calling program should treat messages sent to stdout (except for
218 progress bar messages) as status messages. They can be logged and/or
219 displayed to the user.
223 The calling program should treat messages sent to stderr as error
224 messages. In addition, virt-sparsify exits with a non-zero status
225 code if there was a fatal error.
229 All versions of virt-sparsify have supported the I<--machine-readable>
234 This program returns 0 if successful, or non-zero if there was an
237 =head1 ENVIRONMENT VARIABLES
243 Location of the temporary directory used for the potentially large
244 temporary overlay file.
246 You should ensure there is enough free space in the worst case for a
247 full copy of the source disk (I<virtual> size), or else set C<$TMPDIR>
248 to point to another directory that has enough space.
250 This defaults to C</tmp>.
254 For other environment variables, see L<guestfs(3)/ENVIRONMENT VARIABLES>.
258 L<virt-filesystems(1)>,
267 L<http://libguestfs.org/>.
271 Richard W.M. Jones L<http://people.redhat.com/~rjones/>
275 Copyright (C) 2011 Red Hat Inc.
277 This program is free software; you can redistribute it and/or modify
278 it under the terms of the GNU General Public License as published by
279 the Free Software Foundation; either version 2 of the License, or
280 (at your option) any later version.
282 This program is distributed in the hope that it will be useful,
283 but WITHOUT ANY WARRANTY; without even the implied warranty of
284 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
285 GNU General Public License for more details.
287 You should have received a copy of the GNU General Public License
288 along with this program; if not, write to the Free Software
289 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.