1virt-sparsify(1)            Virtualization Support            virt-sparsify(1)
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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
115           ·   ignore it,
116
117           ·   print a warning and continue,
118
119           ·   warn and wait for the user to press the Return key (this is the
120               default), or:
121
122           ·   fail 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.  "SELECTOR" can be in one of the following
193           formats:
194
195           --key "DEVICE":key:KEY_STRING
196               Use the specified "KEY_STRING" as passphrase.
197
198           --key "DEVICE":file:FILENAME
199               Read the passphrase from FILENAME.
200
201       --keys-from-stdin
202           Read key or passphrase parameters from stdin.  The default is to
203           try to read passphrases from the user by opening /dev/tty.
204
205       --machine-readable
206       --machine-readable=format
207           This option is used to make the output more machine friendly when
208           being parsed by other programs.  See "MACHINE READABLE OUTPUT"
209           below.
210
211       -o option[,option,...]
212           Pass -o option(s) to the qemu-img(1) command to fine-tune the
213           output format.  Options available depend on the output format (see
214           --convert) and the installed version of the qemu-img program.
215
216           You should use -o at most once.  To pass multiple options, separate
217           them with commas, eg:
218
219            virt-sparsify --convert qcow2 \
220              -o cluster_size=512,preallocation=metadata ...
221
222           You cannot use this option and --in-place together.
223
224       -q
225       --quiet
226           This disables progress bars and other unnecessary output.
227
228       --tmp block_device
229       --tmp dir
230           In copying mode only, use the named device or directory as the
231           location of the temporary overlay (see also "TMPDIR" below).
232
233           If the parameter given is a block device, then the block device is
234           written to directly.  Note this erases the existing contents of the
235           block device.
236
237           If the parameter is a directory, then this is the same as setting
238           the "TMPDIR" environment variable.
239
240           You cannot use this option and --in-place together.
241
242       --tmp prebuilt:file
243           In copying mode only, the specialized option --tmp prebuilt:file
244           (where "prebuilt:" is a literal string) causes virt-sparsify to use
245           the qcow2 "file" as temporary space.
246
247           ·   The file must be freshly formatted as qcow2, with indisk as the
248               backing file.
249
250           ·   If you rerun virt-sparsify, you must recreate the file before
251               each run.
252
253           ·   Virt-sparsify does not delete the file.
254
255           This option is used by oVirt which requires a specially formatted
256           temporary file.
257
258       -v
259       --verbose
260           Enable verbose messages for debugging.
261
262       -V
263       --version
264           Display version number and exit.
265
266       -x  Enable tracing of libguestfs API calls.
267
268       --zero partition
269       --zero logvol
270           Zero the contents of the named partition or logical volume in the
271           guest.  All data on the device is lost, but sparsification is
272           excellent!  You can give this option multiple times.
273

IN-PLACE SPARSIFICATION

275       Since virt-sparsify ≥ 1.26, the tool is able to do in-place
276       sparsification (instead of copying from an input disk to an output
277       disk).  This is more efficient.  It is not able to recover quite as
278       much space as copying sparsification.
279
280       To use this mode, specify a disk image which will be modified in place:
281
282        virt-sparsify --in-place disk.img
283
284       Some options are not compatible with this mode: --convert, --compress
285       and -o because they require wholesale disk format changes;
286       --check-tmpdir because large amounts of temporary space are not
287       required.
288
289       In-place sparsification works using discard (a.k.a trim or unmap)
290       support.
291

MACHINE READABLE OUTPUT

293       The --machine-readable option can be used to make the output more
294       machine friendly, which is useful when calling virt-sparsify from other
295       programs, GUIs etc.
296
297       There are two ways to use this option.
298
299       Firstly use the option on its own to query the capabilities of the
300       virt-sparsify binary.  Typical output looks like this:
301
302        $ virt-sparsify --machine-readable
303        virt-sparsify
304        ntfs
305        btrfs
306
307       A list of features is printed, one per line, and the program exits with
308       status 0.
309
310       Secondly use the option in conjunction with other options to make the
311       regular program output more machine friendly.
312
313       At the moment this means:
314
315       1.  Progress bar messages can be parsed from stdout by looking for this
316           regular expression:
317
318            ^[0-9]+/[0-9]+$
319
320       2.  The calling program should treat messages sent to stdout (except
321           for progress bar messages) as status messages.  They can be logged
322           and/or displayed to the user.
323
324       3.  The calling program should treat messages sent to stderr as error
325           messages.  In addition, virt-sparsify exits with a non-zero status
326           code if there was a fatal error.
327
328       All versions of virt-sparsify have supported the --machine-readable
329       option.
330
331       It is possible to specify a format string for controlling the output;
332       see "ADVANCED MACHINE READABLE OUTPUT" in guestfs(3).
333

WINDOWS 8

335       Windows 8 "fast startup" can prevent virt-sparsify from working.  See
336       "WINDOWS HIBERNATION AND WINDOWS 8 FAST STARTUP" in guestfs(3).
337

ENVIRONMENT VARIABLES

339       TMPDIR
340           Location of the temporary directory used for the potentially large
341           temporary overlay file.
342
343           In virt-sparsify ≥ 1.28, you can override this environment variable
344           using the --tmp option.
345
346           You should ensure there is enough free space in the worst case for
347           a full copy of the source disk (virtual size), or else set $TMPDIR
348           to point to another directory that has enough space.
349
350           This defaults to /tmp.
351
352           Note that if $TMPDIR is a tmpfs (eg. if /tmp is on tmpfs, or if you
353           use "TMPDIR=/dev/shm"), tmpfs defaults to a maximum size of half of
354           physical RAM.  If virt-sparsify exceeds this, it will hang.  The
355           solution is either to use a real disk, or to increase the maximum
356           size of the tmpfs mountpoint, eg:
357
358            mount -o remount,size=10G /tmp
359
360           If you are using the --in-place option, then large amounts of
361           temporary space are not required.
362
363       For other environment variables, see "ENVIRONMENT VARIABLES" in
364       guestfs(3).
365

EXIT STATUS

367       This program returns 0 if the operation completed without errors.
368       (This doesn't necessarily mean that space could be freed up.)
369
370       A non-zero exit code indicates an error.
371
372       If the exit code is 3 and the --in-place option was used, that
373       indicates that discard support is not available in libguestfs, so
374       copying mode must be used instead.
375

SEE ALSO

377       virt-df(1), virt-filesystems(1), virt-resize(1), virt-rescue(1),
378       guestfs(3), guestfish(1), truncate(1), fallocate(1), qemu-img(1),
379       http://libguestfs.org/.
380

AUTHOR

382       Richard W.M. Jones http://people.redhat.com/~rjones/
383
385       Copyright (C) 2011-2019 Red Hat Inc.
386

LICENSE

388       This program is free software; you can redistribute it and/or modify it
389       under the terms of the GNU General Public License as published by the
390       Free Software Foundation; either version 2 of the License, or (at your
391       option) any later version.
392
393       This program is distributed in the hope that it will be useful, but
394       WITHOUT ANY WARRANTY; without even the implied warranty of
395       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
396       General Public License for more details.
397
398       You should have received a copy of the GNU General Public License along
399       with this program; if not, write to the Free Software Foundation, Inc.,
400       51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
401

BUGS

403       To get a list of bugs against libguestfs, use this link:
404       https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
405
406       To report a new bug against libguestfs, use this link:
407       https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
408
409       When reporting a bug, please supply:
410
411       ·   The version of libguestfs.
412
413       ·   Where you got libguestfs (eg. which Linux distro, compiled from
414           source, etc)
415
416       ·   Describe the bug accurately and give a way to reproduce it.
417
418       ·   Run libguestfs-test-tool(1) and paste the complete, unedited output
419           into the bug report.
420
421
422
423libguestfs-1.40.1                 2019-01-17                  virt-sparsify(1)
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