[RFC V5 3/5] docs: manpage for xl snapshot command

[Bamvor Jian Zhang <bjzhang@suse.com>]

This file will be a patch for docs/misc/xl.pod.1

=head1 SNAPSHOT

There are two types of snapshots supported by libxl: disk snapshot and domain
snapshot and four types of operations: create, delete, list and revert.

Disk snapshot will only be crash-consistent if the domain is running. Disk
snapshots can also be internal (qcow2) or external (snapshot in one file, delta
in another).

Domain snapshots include disk snapshots and domain state, allowing to resume
the domain from the same state when the snapshot was created. This type of
snapshot is also referred to as a domain checkpoint or system checkpoint.

=over 4

=item B<snapshot-create> [I<configfile>] [I<OPTIONS>] I<domain-id>

create domain/disk snapshot.

The create subcommand takes a config file as first argument: see
L<xl.snapshot.cfg(5)> for full details of that file format and possible options.
If I<configfile> is missing, B<XL> creates the snapshot of domain from options.
I<configfile> has to be an absolute path to a file.
It is allowed to use both I<configfile> and I<OPTIONS>. Any conflict will be
reportted and the program will exit. However, it is highly recommended that use
I<configfile> or I<OPTIONS> alone.
This command allows dryrun mode. It will print domain snapshot configuration in
libxl-json format after parsing options and the config file and checking the
flags conflict.

B<OPTIONS>

=over 4

=item B<-n>

domain/disk snapshot name. if ignored, it will be the epoch second from 1, Jan
1970.

=item B<-D>, B<--disk-only>

create the internal disk snapshot for all disk(s) except the read-only disk
(e.g. cdrom). For external disk snapshot, user should give the proper options
(such as the external file and format) in I<configfile>.

=back

=item B<snapshot-delete> [I<OPTIONS>] I<domain-id>

delete domain/disk snapshot according to the snapshot configuration file, which
may include the memory check point file, the disk snapshot state/file and the
configuration file.

B<OPTIONS>

=over 4

=item B<-n>

snapshot name.

=back

=item B<snapshot-list> [I<OPTIONS>] I<domain-id>

Prints information for one or all snapshots for <domain-id>. If no snapshots
are specified it prints out information about all snapshots for specific domain

B<OPTIONS>

=over 4

=item B<-n>

snapshot name.

=item B<-l>, B<--long>

list the details for specific snapshot or all snapshots of specific domain.

=back

=item B<snapshot-revert> [I<OPTIONS>] I<domain-id>

revert domain snapshot according to domain snapshot configuration file.

B<OPTIONS>

=over 4

=item B<-n>

snapshot name.

=back

=back