Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
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Eric Blake 4201a7ea1c snapshot: new XML for external system checkpoint
Each <domainsnapshot> can now contain an optional <memory>
element that describes how the VM state was handled, similar
to disk snapshots.  The new element will always appear in
output; for back-compat, an input that lacks the element will
assume 'no' or 'internal' according to the domain state.

Along with this change, it is now possible to pass <disks> in
the XML for an offline snapshot; this also needs to be wired up
in a future patch, to make it possible to choose internal vs.
external on a per-disk basis for each disk in an offline domain.
At that point, using the --disk-only flag for an offline domain
will be able to work.

For some examples below, remember that qemu supports the
following snapshot actions:

qemu-img: offline external and internal disk
savevm: online internal VM and disk
migrate: online external VM
transaction: online external disk

=====
<domainsnapshot>
  <memory snapshot='no'/>
  ...
</domainsnapshot>

implies that there is no VM state saved (mandatory for
offline and disk-only snapshots, not possible otherwise);
using qemu-img for offline domains and transaction for online.

=====
<domainsnapshot>
  <memory snapshot='internal'/>
  ...
</domainsnapshot>

state is saved inside one of the disks (as in qemu's 'savevm'
system checkpoint implementation).  If needed in the future,
we can also add an attribute pointing out _which_ disk saved
the internal state; maybe disk='vda'.

=====
<domainsnapshot>
  <memory snapshot='external' file='/path/to/state'/>
  ...
</domainsnapshot>

This is not wired up yet, but future patches will allow this to
control a combination of 'virsh save /path/to/state' plus disk
snapshots from the same point in time.

=====

So for 1.0.1 (and later, as needed), I plan to implement this table
of combinations, with '*' designating new code and '+' designating
existing code reached through new combinations of xml and/or the
existing DISK_ONLY flag:

domain  memory  disk   disk-only | result
-----------------------------------------
offline omit    omit   any       | memory=no disk=int, via qemu-img
offline no      omit   any       |+memory=no disk=int, via qemu-img
offline omit/no no     any       | invalid combination (nothing to snapshot)
offline omit/no int    any       |+memory=no disk=int, via qemu-img
offline omit/no ext    any       |*memory=no disk=ext, via qemu-img
offline int/ext any    any       | invalid combination (no memory to save)
online  omit    omit   off       | memory=int disk=int, via savevm
online  omit    omit   on        | memory=no disk=default, via transaction
online  omit    no/ext off       | unsupported for now
online  omit    no     on        | invalid combination (nothing to snapshot)
online  omit    ext    on        | memory=no disk=ext, via transaction
online  omit    int    off       |+memory=int disk=int, via savevm
online  omit    int    on        | unsupported for now
online  no      omit   any       |+memory=no disk=default, via transaction
online  no      no     any       | invalid combination (nothing to snapshot)
online  no      int    any       | unsupported for now
online  no      ext    any       |+memory=no disk=ext, via transaction
online  int/ext any    on        | invalid combination (disk-only vs. memory)
online  int     omit   off       |+memory=int disk=int, via savevm
online  int     no/ext off       | unsupported for now
online  int     int    off       |+memory=int disk=int, via savevm
online  ext     omit   off       |*memory=ext disk=default, via migrate+trans
online  ext     no     off       |+memory=ext disk=no, via migrate
online  ext     int    off       | unsupported for now
online  ext     ext    off       |*memory=ext disk=ext, via migrate+transaction

* docs/schemas/domainsnapshot.rng (memory): New RNG element.
* docs/formatsnapshot.html.in: Document it.
* src/conf/snapshot_conf.h (virDomainSnapshotDef): New fields.
* src/conf/domain_conf.c (virDomainSnapshotDefFree)
(virDomainSnapshotDefParseString, virDomainSnapshotDefFormat):
Manage new fields.
* tests/domainsnapshotxml2xmltest.c: New test.
* tests/domainsnapshotxml2xmlin/*.xml: Update existing tests.
* tests/domainsnapshotxml2xmlout/*.xml: Likewise.
2012-11-02 09:56:23 -06:00
.gnulib@d245e6ddd6 maint: update to latest gnulib 2012-10-22 20:25:44 -06:00
build-aux Document bracket whitespace rules & add syntax-check rule 2012-11-02 14:00:32 +00:00
daemon Remove spurious whitespace between function name & open brackets 2012-11-02 13:36:49 +00:00
docs snapshot: new XML for external system checkpoint 2012-11-02 09:56:23 -06:00
examples tests: Fix domain-events python test 2012-10-16 16:37:29 +02:00
gnulib build: fix fresh checkout on RHEL5 2012-04-19 17:11:43 -06:00
include blockjob: return appropriate event and info 2012-10-27 07:43:38 -06:00
m4 build: improve FORTIFY_SOURCE usage 2012-10-23 14:00:32 -06:00
po Release of libvirt-1.0.0 2012-11-02 12:08:11 +08:00
python Remove spurious whitespace between function name & open brackets 2012-11-02 13:36:49 +00:00
src snapshot: new XML for external system checkpoint 2012-11-02 09:56:23 -06:00
tests snapshot: new XML for external system checkpoint 2012-11-02 09:56:23 -06:00
tools Remove spurious whitespace between function name & open brackets 2012-11-02 13:36:49 +00:00
.dir-locals.el build: avoid tabs that failed syntax-check 2012-09-06 09:43:46 -06:00
.gitignore gitignore: Ignore 'tags' 2012-10-31 16:47:34 +01:00
.gitmodules make .gnulib a submodule 2009-07-08 16:17:51 +02:00
.mailmap Autogenerate AUTHORS 2012-10-19 12:44:56 -04:00
AUTHORS.in Remove a couple duplicates from AUTHORS.in 2012-10-22 16:19:38 -04:00
autobuild.sh Switch automated builds to use Mingw64 toolchain instead of Mingw32 2012-06-25 10:41:10 +01:00
autogen.sh build: avoid infinite autogen loop 2012-10-01 09:47:38 -06:00
bootstrap maint: regenerate bootstrap 2012-07-27 09:34:04 -06:00
bootstrap.conf build: prefer mkostemp for multi-thread safety 2012-10-31 10:06:10 -06:00
cfg.mk Document bracket whitespace rules & add syntax-check rule 2012-11-02 14:00:32 +00:00
ChangeLog-old virterror.c: Fix several spelling mistakes 2012-02-03 11:32:51 -07:00
configure.ac Release of libvirt-1.0.0 2012-11-02 12:08:11 +08:00
COPYING.LIB remove all trailing blank lines 2009-07-16 15:06:42 +02:00
HACKING Document bracket whitespace rules & add syntax-check rule 2012-11-02 14:00:32 +00:00
libvirt.pc.in build: silence warning from autoconf 2012-05-30 09:22:02 -06:00
libvirt.spec.in Release of libvirt-1.0.0 2012-11-02 12:08:11 +08:00
Makefile.am Autogenerate AUTHORS 2012-10-19 12:44:56 -04:00
Makefile.nonreentrant Ban use of all inet_* functions 2010-10-22 11:59:23 +01:00
mingw-libvirt.spec.in parallels: add driver skeleton 2012-08-01 11:44:26 +08:00
README Correct typos in the documentation (Atsushi SAKAI) 2008-01-24 10:15:13 +00:00
README-hacking maint: relax git minimum version 2010-02-24 14:29:27 -05:00
run.in syntax-check: fix run.in 2012-09-18 13:59:53 +02:00
TODO Update todo list file to point at bugzilla/website 2010-10-13 16:45:26 +01:00

         LibVirt : simple API for virtualization

  Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.

Daniel Veillard <veillard@redhat.com>