From 66ec00ab3eeb10d2c4c7397886dcce15e1458327 Mon Sep 17 00:00:00 2001 From: Michael Weiser Date: Fri, 3 Jan 2020 19:43:25 +0100 Subject: [PATCH] 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 Reviewed-by: Daniel Henrique Barboza --- 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 56c0a0c153..6446a903ca 100644 --- a/docs/manpages/virsh.rst +++ b/docs/manpages/virsh.rst @@ -6970,7 +6970,7 @@ 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 @@ -6980,7 +6980,7 @@ 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 @@ -6988,6 +6988,13 @@ 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 existing 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 ---------------