=head1 NAME

virt-v2v-inspector - Estimate disk space needed before virt-v2v conversion

=head1 SYNOPSIS

 virt-v2v-inspector [-i* options]
                    [virt-customize options]
                    guest
                    [-O output.xml]

=head1 DESCRIPTION

Virt-v2v-inspector is a companion tool for L<virt-v2v(1)> which can be
used before conversion to estimate the number of output disks and disk
space that will be required to complete the virt-v2v conversion.  The
common use for this is to preallocate target disks on management
systems that need this (like Kubevirt).

This manual page only documents the estimation feature, not all of the
I<-i*> options which are the same as virt-v2v.  You should read
L<virt-v2v(1)> first.

=head2 Selecting the input guest

You can run virt-v2v-inspector with the same I<-i*> options as
virt-v2v.  (Don't use any I<-o*> options).  This will select the guest
that you want to estimate.

For example to estimate the space required for a guest in a stored
local disk called F<filename.img> you could do:

 virt-v2v-inspector -i disk filename.img

=head2 Output

The output from this tool is an XML document.

=over 4

=item *

Fields which are annotated with an C<estimated='true'> attribute are
estimated.  Virt-v2v cannot always know exactly the final size of some
things, such as the exact real size of the output disk, since there
might be small perturbations between runs.  Estimates are usually very
close to the final values.

=item *

Numbers representing sizes are always given in bytes.

=item *

By default the output is written to stdout.  This is useful when using
the program interactively.  However if you want to use this tool from
another program it is better to send the output to a specific file
using I<-O output.xml>

=back

 <?xml version='1.0' encoding='utf-8'?>
 <v2v-inspection>
   <program>virt-v2v-inspector</program>
   <package>virt-v2v</package>
   <version>2.1.9</version>

The E<lt>programE<gt>, E<lt>packageE<gt> and E<lt>versionE<gt>
elements refer to the current version of virt-v2v-inspector and are
useful for debugging.  Make sure you use the same version of
virt-v2v-inspector and virt-v2v.

   <disks>
     <disk index='0'>
       <virtual-size>6442450944</virtual-size>
       <allocated estimated='true'>1400897536</allocated>
     </disk>
     <disk index='1'>
       <virtual-size>6442450944</virtual-size>
       <allocated estimated='true'>45131520</allocated>
     </disk>
   </disks>

The E<lt>disksE<gt> element lists information about each guest disk.
The example virtual machine above has two disks.
E<lt>virtual-sizeE<gt> describes the size of the disk as seen from
inside the guest, while E<lt>allocatedE<gt> is an estimate of how much
storage will be needed on the host after conversion.  This is assuming
you use S<I<-oa sparse>> - see the notes below.

   <operatingsystem>
     <name>linux</name>
     <distro>fedora</distro>
     <osinfo>fedora32</osinfo>
     <arch>x86_64</arch>
     [...]
   </operatingsystem>

The E<lt>operatingsystemE<gt> element lists information about the
guest operating system gleaned during conversion, in a manner similar
to the L<virt-inspector(1)> tool from guestfs-tools.

=head2 Output allocation mode and output format

Virt-v2v supports selecting the output allocation mode (I<-oa> option)
and output format (I<-of> option, eg. S<I<-of qcow2>>).  Since it is
difficult to predict the effect of these options on the actual space
occupied by the final image this tool does not account for them.

As a rule of thumb:

=over 4

=item S<virt-v2v -oa preallocated>

causes the disk images on the target to consume their full virtual
size (excluding the effect of zero allocations will depends so much on
the underlying storage that it is often hard even for experts to
predict).

=item S<virt-v2v -of qcow2>

uses the QCOW2 format where supported which means that the apparent
size of the file will be equal to its sparse size, but otherwise
should not affect estimates very much.

=back

=head1 OPTIONS

=over 4

=item B<--help>

Display help.

=item B<-O> F<output.xml>

Write the output to a file called F<output.xml>.

=item B<-O ->

Write the output to stdout.  This is also the default if the I<-O>
option is omitted.

=item B<-v>

=item B<--verbose>

Enable verbose messages for debugging.

=item B<-V>

=item B<--version>

Display version number and exit.

=item B<-x>

Enable tracing of libguestfs API calls.

=item B<-i> ...

=item B<-ic> ...

=item B<-if> ...

=item B<-io> ...

=item B<-ip> ...

=item B<-it> ...

All of the I<-i*> options supported by virt-v2v and also supported by
virt-v2v-inspector.

=item B<-b> ...

=item B<--bridge> ...

=item B<--collect> ...

=item B<--collect-output> ...

=item B<--colors>

=item B<--colours>

=item B<--echo-keys>

=item B<--key> ...

=item B<--keys-from-stdin>

=item B<--mac> ...

=item B<--machine-readable>

=item B<--machine-readable>=format

=item B<-m> MB

=item B<--memsize> MB

=item B<-n> ...

=item B<--network> ...

=item B<--no-fstrim>

=item B<-q>

=item B<--quiet>

=item B<--root> ...

=item B<--smp> N

=item B<--wrap>

These options work in the same way as the equivalent virt-v2v options.

=back

=head1 FILES

Files used are the same as for virt-v2v.  See L<virt-v2v(1)/FILES>.

=head1 ENVIRONMENT VARIABLES

Environment variables used are the same as for virt-v2v.  See
L<virt-v2v(1)/ENVIRONMENT VARIABLES>.

=head1 SEE ALSO

L<virt-v2v(1)>,
L<virt-p2v(1)>,
L<virt-inspector(1)>,
L<guestfs(3)>,
L<guestfish(1)>,
L<qemu-img(1)>,
L<nbdkit(1)>,
L<http://libguestfs.org/>.

=head1 AUTHORS

Matthew Booth

Cédric Bosdonnat

Laszlo Ersek

Tomáš Golembiovský

Shahar Havivi

Richard W.M. Jones

Roman Kagan

Mike Latimer

Nir Soffer

Pino Toscano

Xiaodai Wang

Ming Xie

Tingting Zheng

=head1 COPYRIGHT

Copyright (C) 2009-2025 Red Hat Inc.
