docs/interop/live-block-operations.rst

18 synchronize data from a disk image chain (including current active disk)
34 Disk image backing chain notation
37 A simple disk image chain.  (This can be created live using QMP
54 files in a disk image backing chain:
56 (1) Directional: 'base' and 'top'.  Given the simple disk image chain
62     simple disk image chain from the above, disk image [A] is referred
85                 (a) QEMU rewrites the backing chain to remove
99     chain).  Since QEMU 2.0, this includes "active ``block-commit``"
105                 (a) QEMU rewrites the backing chain to remove reference
149 image chain, and continue to refer to the disks using their
171 Example disk image chain
174 We will use the below disk image chain (and occasionally spelling it
182 to the rightmost image in a disk image chain.)
184 The above image chain can be created by invoking
214 In our disk image chain::
241 Given our original example disk image chain from earlier::
245 The disk image chain can be shortened in one of the following different
252     *while* the guest is running.  The resulting chain will be a
260 (2) Taking the same example disk image chain mentioned earlier, merge
264     [A].  The resulting chain will be::
271     with the original example disk image chain, with a total of four
276     streaming" of [B] into [C], the resulting image chain will be (where
287 ``block-stream`` will flatten the entire chain); ``qmp-shell`` (and its
333 image in a disk image chain where live QEMU will be writing to, into the
337 Again, starting afresh with our example disk image chain, where live
338 QEMU is writing to the right-most image in the chain, [D]::
342 The disk image chain can be shortened in one of the following ways:
347     chain is the following, where image [C] is adjusted to point at [A]
353     resulting chain, where image [D] is adjusted to point to image [A]
361     image [A].  The resulting chain (in this case, a consolidated single
367     resulting chain::
372     [B].  The resulting chain::
397 to point to image [A], and the original 4-image chain will end up being
428 convert a disk image chain such as this::
506 Synchronize a running disk image chain (all or part of it) to a target
509 Again, given our familiar disk image chain::
514 allows you to copy data from the entire chain into a single target image
539     image chain (or only the top-most image, depending on the ``sync``
549 *which* part of the disk image chain will be copied to the target.
552 (1) ``full`` -- Synchronize the content of entire disk image chain to
556     in the chain to the target
581 To copy the contents of the entire disk image chain, from [A] all the
596 The ``"sync": "full"``, from the above, means: copy the *entire* chain
630     content from the entire chain, [A] to [D])::
653 from the disk image chain.
664 Given the disk image chain::
668 Instead of copying content from the entire chain, synchronize *only* the
674     chain, involving images [A], [B], and [C], visible via other means
679 the "active layer", and not the rest of the image chain, is copied to
687 chain -- from images [A] to [C] -- are already expected to exist in some
711 Given the disk image chain on source QEMU::
715 On the destination host, it is expected that the contents of the chain
812 entire disk image chain, to a target, using ``blockdev-mirror`` would be:
814 (0) Create the QCOW2 overlays, to arrive at a backing chain of desired
823     entire chain to the target).  And notice the event
835 (7) Then, finally, compare the contents of the disk image chain, and
843 Given the disk image chain::
847 To copy the contents of the entire disk image chain, from [A] all the
950 Yet again, starting afresh with our example disk image chain::
955 [D], from the above chain, the following is the syntax.  (If the target
993 of an entire disk image chain, to a target, using ``blockdev-backup``
996 (0) Create the QCOW2 overlays, to arrive at a backing chain of desired
1005     entire chain to the target).  And notice the event
1011 (5) Then, finally, compare the contents of the disk image chain, and
1021 Given a disk image chain of depth 1 where image [B] is the active
1026 The following is the procedure to copy the content from the entire chain
1064 image chain, consisting of images [A] and [B] to the target image
1108 point-in-time backup of the disk image chain -- i.e. contents from
1113 with the disk image chain is to compare the backup and the contents of
1114 the chain, you should see "Images are identical".  (NB: this is assuming