1virt-sparsify(1)            Virtualization Support            virt-sparsify(1)
2
3
4

NAME

6       virt-sparsify - Make a virtual machine disk sparse
7

SYNOPSIS

9        virt-sparsify [--options] indisk outdisk
10
11        virt-sparsify [--options] --in-place disk
12

WARNING

14       Using "virt-sparsify" on live virtual machines, or concurrently with
15       other disk editing tools, can be dangerous, potentially causing disk
16       corruption.  The virtual machine must be shut down before you use this
17       command, and disk images must not be edited concurrently.
18

DESCRIPTION

20       Virt-sparsify is a tool which can make a virtual machine disk (or any
21       disk image) sparse a.k.a. thin-provisioned.  This means that free space
22       within the disk image can be converted back to free space on the host.
23
24       Virt-sparsify can locate and sparsify free space in most filesystems
25       (eg. ext2/3/4, btrfs, NTFS, etc.), and also in LVM physical volumes.
26
27       Virt-sparsify can also convert between some disk formats, for example
28       converting a raw disk image to a thin-provisioned qcow2 image.
29
30       Virt-sparsify can operate on any disk image, not just ones from virtual
31       machines.  However if a virtual machine has multiple disks and uses
32       volume management, then virt-sparsify will work but not be very
33       effective (http://bugzilla.redhat.com/887826).
34
35   IMPORTANT NOTE ABOUT SPARSE OUTPUT IMAGES
36       If the input is raw, then the default output is raw sparse.  You must
37       check the output size using a tool that understands sparseness such as
38       "du -sh".  It can make a huge difference:
39
40        $ ls -lh test1.img
41        -rw-rw-r--. 1 rjones rjones 100M Aug  8 08:08 test1.img
42        $ du -sh test1.img
43        3.6M   test1.img
44
45       (Compare the apparent size 100M vs the actual size 3.6M)
46
47   IMPORTANT LIMITATIONS
48       •   The virtual machine must be shut down before using this tool.
49
50       •   Virt-sparsify may require up to 2x the virtual size of the source
51           disk image (1 temporary copy + 1 destination image).  This is in
52           the worst case and usually much less space is required.
53
54           If you are using the --in-place option, then large amounts of
55           temporary space are not required.
56
57       •   Virt-sparsify cannot resize disk images.  To do that, use
58           virt-resize(1).
59
60       •   Virt-sparsify cannot handle encrypted disks.  Libguestfs supports
61           encrypted disks, but encrypted disks themselves cannot be
62           sparsified.
63
64       •   Virt-sparsify cannot yet sparsify the space between partitions.
65           Note that this space is often used for critical items like
66           bootloaders so it's not really unused.
67
68       •   In copy mode, qcow2 internal snapshots are not copied over to the
69           destination image.
70
71       You may also want to read the manual pages for the associated tools
72       virt-filesystems(1) and virt-df(1) before starting.
73

EXAMPLES

75       Typical usage is:
76
77        virt-sparsify indisk outdisk
78
79       which copies "indisk" to "outdisk", making the output sparse.
80       "outdisk" is created, or overwritten if it already exists.  The format
81       of the input disk is detected (eg. qcow2) and the same format is used
82       for the output disk.
83
84       To convert between formats, use the --convert option:
85
86        virt-sparsify disk.raw --convert qcow2 disk.qcow2
87
88       Virt-sparsify tries to zero and sparsify free space on every filesystem
89       it can find within the source disk image.  You can get it to ignore
90       (don't zero free space on) certain filesystems by doing:
91
92        virt-sparsify --ignore /dev/sda1 indisk outdisk
93
94       See virt-filesystems(1) to get a list of filesystems within a disk
95       image.
96
97       Since virt-sparsify ≥ 1.26, you can now sparsify a disk image in place
98       by doing:
99
100        virt-sparsify --in-place disk.img
101

OPTIONS

103       --help
104           Display help.
105
106       --check-tmpdir ignore
107       --check-tmpdir continue
108       --check-tmpdir warn
109       --check-tmpdir fail
110           Check if "TMPDIR" or --tmp directory has enough space to complete
111           the operation.  This is just an estimate.
112
113           If the check indicates a problem, then you can either:
114
115ignore it,
116
117           •   print a warning and continue,
118
119warn and wait for the user to press the Return key (this is the
120               default), or:
121
122fail and exit.
123
124           You cannot use this option and --in-place together.
125
126       --colors
127       --colours
128           Use ANSI colour sequences to colourize messages.  This is the
129           default when the output is a tty.  If the output of the program is
130           redirected to a file, ANSI colour sequences are disabled unless you
131           use this option.
132
133       --compress
134           Compress the output file.  This only works if the output format is
135           "qcow2".
136
137           You cannot use this option and --in-place together.
138
139       --convert raw
140       --convert qcow2
141       --convert [other formats]
142           Use "output-format" as the format for the destination image.  If
143           this is not specified, then the input format is used.
144
145           Supported and known-working output formats are: "raw", "qcow2",
146           "vdi".
147
148           You can also use any format supported by the qemu-img(1) program,
149           eg. "vmdk", but support for other formats is reliant on qemu.
150
151           Specifying the --convert option is usually a good idea, because
152           then virt-sparsify doesn't need to try to guess the input format.
153
154           For fine-tuning the output format, see: --compress, -o.
155
156           You cannot use this option and --in-place together.
157
158       --echo-keys
159           When prompting for keys and passphrases, virt-sparsify normally
160           turns echoing off so you cannot see what you are typing.  If you
161           are not worried about Tempest attacks and there is no one else in
162           the room you can specify this flag to see what you are typing.
163
164       --format raw
165       --format qcow2
166           Specify the format of the input disk image.  If this flag is not
167           given then it is auto-detected from the image itself.
168
169           If working with untrusted raw-format guest disk images, you should
170           ensure the format is always specified.
171
172       --ignore filesystem
173       --ignore volgroup
174           Ignore the named filesystem.
175
176           When not using --in-place: Free space on the filesystem will not be
177           zeroed, but existing blocks of zeroes will still be sparsified.
178
179           When using --in-place, the filesystem is ignored completely.
180
181           In the second form, this ignores the named volume group.  Use the
182           volume group name without the /dev/ prefix, eg. --ignore vg_foo
183
184           You can give this option multiple times.
185
186       --in-place
187           Do in-place sparsification instead of copying sparsification.  See
188           "IN-PLACE SPARSIFICATION" below.
189
190       --key SELECTOR
191           Specify a key for LUKS, to automatically open a LUKS device when
192           using the inspection.  "ID" can be either the libguestfs device
193           name, or the UUID of the LUKS device.
194
195           --key "ID":key:KEY_STRING
196               Use the specified "KEY_STRING" as passphrase.
197
198           --key "ID":file:FILENAME
199               Read the passphrase from FILENAME.
200
201           --key "ID":clevis
202               Attempt passphrase-less unlocking for "ID" with Clevis, over
203               the network.  Please refer to "ENCRYPTED DISKS" in guestfs(3)
204               for more information on network-bound disk encryption (NBDE).
205
206               Note that if any such option is present on the command line,
207               QEMU user networking will be automatically enabled for the
208               libguestfs appliance.
209
210       --keys-from-stdin
211           Read key or passphrase parameters from stdin.  The default is to
212           try to read passphrases from the user by opening /dev/tty.
213
214           If there are multiple encrypted devices then you may need to supply
215           multiple keys on stdin, one per line.
216
217       --machine-readable
218       --machine-readable=format
219           This option is used to make the output more machine friendly when
220           being parsed by other programs.  See "MACHINE READABLE OUTPUT"
221           below.
222
223       -o option[,option,...]
224           Pass -o option(s) to the qemu-img(1) command to fine-tune the
225           output format.  Options available depend on the output format (see
226           --convert) and the installed version of the qemu-img program.
227
228           You should use -o at most once.  To pass multiple options, separate
229           them with commas, eg:
230
231            virt-sparsify --convert qcow2 \
232              -o cluster_size=512,preallocation=metadata ...
233
234           You cannot use this option and --in-place together.
235
236       -q
237       --quiet
238           This disables progress bars and other unnecessary output.
239
240       --tmp block_device
241       --tmp dir
242           In copying mode only, use the named device or directory as the
243           location of the temporary overlay (see also "TMPDIR" below).
244
245           If the parameter given is a block device, then the block device is
246           written to directly.  Note this erases the existing contents of the
247           block device.
248
249           If the parameter is a directory, then this is the same as setting
250           the "TMPDIR" environment variable.
251
252           You cannot use this option and --in-place together.
253
254       --tmp prebuilt:file
255           In copying mode only, the specialized option --tmp prebuilt:file
256           (where "prebuilt:" is a literal string) causes virt-sparsify to use
257           the qcow2 "file" as temporary space.
258
259           •   The file must be freshly formatted as qcow2, with indisk as the
260               backing file.
261
262           •   If you rerun virt-sparsify, you must recreate the file before
263               each run.
264
265           •   Virt-sparsify does not delete the file.
266
267           This option is used by oVirt which requires a specially formatted
268           temporary file.
269
270       -v
271       --verbose
272           Enable verbose messages for debugging.
273
274       -V
275       --version
276           Display version number and exit.
277
278       --wrap
279           Wrap error, warning, and informative messages.  This is the default
280           when the output is a tty.  If the output of the program is
281           redirected to a file, wrapping is disabled unless you use this
282           option.
283
284       -x  Enable tracing of libguestfs API calls.
285
286       --zero partition
287       --zero logvol
288           Zero the contents of the named partition or logical volume in the
289           guest.  All data on the device is lost, but sparsification is
290           excellent!  You can give this option multiple times.
291

IN-PLACE SPARSIFICATION

293       Since virt-sparsify ≥ 1.26, the tool is able to do in-place
294       sparsification (instead of copying from an input disk to an output
295       disk).  This is more efficient.  It is not able to recover quite as
296       much space as copying sparsification.
297
298       To use this mode, specify a disk image which will be modified in place:
299
300        virt-sparsify --in-place disk.img
301
302       Some options are not compatible with this mode: --convert, --compress
303       and -o because they require wholesale disk format changes;
304       --check-tmpdir because large amounts of temporary space are not
305       required.
306
307       In-place sparsification works using discard (a.k.a trim or unmap)
308       support.
309

MACHINE READABLE OUTPUT

311       The --machine-readable option can be used to make the output more
312       machine friendly, which is useful when calling virt-sparsify from other
313       programs, GUIs etc.
314
315       There are two ways to use this option.
316
317       Firstly use the option on its own to query the capabilities of the
318       virt-sparsify binary.  Typical output looks like this:
319
320        $ virt-sparsify --machine-readable
321        virt-sparsify
322        ntfs
323        btrfs
324
325       A list of features is printed, one per line, and the program exits with
326       status 0.
327
328       Secondly use the option in conjunction with other options to make the
329       regular program output more machine friendly.
330
331       At the moment this means:
332
333       1.  Progress bar messages can be parsed from stdout by looking for this
334           regular expression:
335
336            ^[0-9]+/[0-9]+$
337
338       2.  The calling program should treat messages sent to stdout (except
339           for progress bar messages) as status messages.  They can be logged
340           and/or displayed to the user.
341
342       3.  The calling program should treat messages sent to stderr as error
343           messages.  In addition, virt-sparsify exits with a non-zero status
344           code if there was a fatal error.
345
346       All versions of virt-sparsify have supported the --machine-readable
347       option.
348
349       It is possible to specify a format string for controlling the output;
350       see "ADVANCED MACHINE READABLE OUTPUT" in guestfs(3).
351

WINDOWS 8

353       Windows 8 "fast startup" can prevent virt-sparsify from working.  See
354       "WINDOWS HIBERNATION AND WINDOWS 8 FAST STARTUP" in guestfs(3).
355

ENVIRONMENT VARIABLES

357       TMPDIR
358           Location of the temporary directory used for the potentially large
359           temporary overlay file.
360
361           In virt-sparsify ≥ 1.28, you can override this environment variable
362           using the --tmp option.
363
364           You should ensure there is enough free space in the worst case for
365           a full copy of the source disk (virtual size), or else set $TMPDIR
366           to point to another directory that has enough space.
367
368           This defaults to /tmp.
369
370           Note that if $TMPDIR is a tmpfs (eg. if /tmp is on tmpfs, or if you
371           use "TMPDIR=/dev/shm"), tmpfs defaults to a maximum size of half of
372           physical RAM.  If virt-sparsify exceeds this, it will hang.  The
373           solution is either to use a real disk, or to increase the maximum
374           size of the tmpfs mountpoint, eg:
375
376            mount -o remount,size=10G /tmp
377
378           If you are using the --in-place option, then large amounts of
379           temporary space are not required.
380
381       For other environment variables, see "ENVIRONMENT VARIABLES" in
382       guestfs(3).
383

EXIT STATUS

385       This program returns 0 if the operation completed without errors.
386       (This doesn't necessarily mean that space could be freed up.)
387
388       A non-zero exit code indicates an error.
389
390       If the exit code is 3 and the --in-place option was used, that
391       indicates that discard support is not available in libguestfs, so
392       copying mode must be used instead.
393

SEE ALSO

395       virt-df(1), virt-filesystems(1), virt-resize(1), virt-rescue(1),
396       guestfs(3), guestfish(1), truncate(1), fallocate(1), qemu-img(1),
397       http://libguestfs.org/.
398

AUTHOR

400       Richard W.M. Jones http://people.redhat.com/~rjones/
401
403       Copyright (C) 2011-2023 Red Hat Inc.
404

LICENSE

406       This program is free software; you can redistribute it and/or modify it
407       under the terms of the GNU General Public License as published by the
408       Free Software Foundation; either version 2 of the License, or (at your
409       option) any later version.
410
411       This program is distributed in the hope that it will be useful, but
412       WITHOUT ANY WARRANTY; without even the implied warranty of
413       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
414       General Public License for more details.
415
416       You should have received a copy of the GNU General Public License along
417       with this program; if not, write to the Free Software Foundation, Inc.,
418       51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
419

BUGS

421       To get a list of bugs against libguestfs, use this link:
422       https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
423
424       To report a new bug against libguestfs, use this link:
425       https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
426
427       When reporting a bug, please supply:
428
429       •   The version of libguestfs.
430
431       •   Where you got libguestfs (eg. which Linux distro, compiled from
432           source, etc)
433
434       •   Describe the bug accurately and give a way to reproduce it.
435
436       •   Run libguestfs-test-tool(1) and paste the complete, unedited output
437           into the bug report.
438
439
440
441guestfs-tools-1.50.1              2023-04-06                  virt-sparsify(1)
Impressum