Re: [libvirt] [PATCH v2 3/3] docs: Add snapshot-revert qemu managedsave force

Add documentation for additional reason why snapshot-revert might need to be forced. This explains why restoring an inactive snapshot while there is managed saved state is refused by default. Signed-off-by: Michael Weiser <michael.weiser(a)gmx.de&gt; Cc: Cole Robinson <crobinso(a)redhat.com&gt; --- docs/manpages/virsh.rst | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst index f5f962cba1..09be872fdf 100644 --- a/docs/manpages/virsh.rst +++ b/docs/manpages/virsh.rst @@ -6951,7 +6951,7 @@ no vm state leaves the domain in an inactive state. Passing either the transient domains cannot be inactive, it is required to use one of these flags when reverting to a disk snapshot of a transient domain. -There are two cases where a snapshot revert involves extra risk, which +There are a number of cases where a snapshot revert involves extra risk, which requires the use of *--force* to proceed: * One is the case of a snapshot that lacks full domain information for @@ -6961,7 +6961,7 @@ requires the use of *--force* to proceed: libvirt that the snapshot is compatible with the current configuration (and if it is not, the domain will likely fail to run). - * The other is the case of reverting from a running domain to an active + * Another is the case of reverting from a running domain to an active state where a new hypervisor has to be created rather than reusing the existing hypervisor, because it implies drawbacks such as breaking any existing VNC or Spice connections; this condition happens with an active @@ -6969,6 +6969,13 @@ requires the use of *--force* to proceed: an inactive snapshot that is combined with the *--start* or *--pause* flag. + * Also, libvirt will refuse to restore snapshots of inactive qemu domains

+ while there is managed saved state. This is because those snapshots do not + contain memory state and will therefore not replace the exising memory

+ state. This ends up switching a disk underneath a running system and will + likely cause extensive filesystem corruption or crashes due to swap content + mismatches when run. + snapshot-delete ---------------