[pve-devel] [PATCH v3 docs] qm: add guest agent section

Aaron Lauterer a.lauterer at proxmox.com
Mon Jan 25 15:54:09 CET 2021

Signed-off-by: Aaron Lauterer <a.lauterer at proxmox.com>
changes v2->v3: incorporated suggestions from Oguz, Stoiko and Thomas

Over christmas and NYE I forgot about this patch series that's why it
took some time for v3 :/

 qm.adoc | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/qm.adoc b/qm.adoc
index 9c54903..0d9c10e 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -917,6 +917,63 @@ start after those where the parameter is set. Further, this parameter can only
 be enforced between virtual machines running on the same host, not
+Qemu Guest Agent
+The Qemu Guest Agent is a service which runs inside the VM, providing a
+communication channel between the host and the guest. It is used to exchange
+information and allows the host to issue commands to the guest.
+For example, the IP addresses in the VM summary panel are fetched via the guest
+Or when starting a backup, the guest is told via the guest agent to sync
+outstanding writes via the 'fs-freeze' and 'fs-thaw' commands.
+For the guest agent to work properly the following steps must be taken:
+* install the agent in the guest and make sure it is running
+* enable the communication via the agent in {pve}
+Install Guest Agent
+For most Linux distributions, the guest agent is available. The package is
+usually named `qemu-guest-agent`.
+For Windows, it can be installed from the
+VirtIO driver ISO].
+Enable Guest Agent Communication
+Communication from {pve} with the guest agent can be enabled in the VM's
+*Options* panel. A fresh start of the VM is necessary for the changes to take
+It is possible to enable the 'Run guest-trim' option. With this enabled,
+{pve} will issue a trim command to the guest after the following
+operations that have the potential to write out zeros to the storage:
+* moving a disk to another storage
+* live migrating a VM to another node with local storage
+On a thin provisioned storage, this can help to free up unused space.
+.VM does not shut down
+Make sure the guest agent is installed and running.
+Once the guest agent is enabled, {pve} will send power commands like
+'shutdown' via the guest agent. If the guest agent is not running, commands
+cannot get executed properly and the shutdown command will run into a timeout.
 SPICE Enhancements

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