+If you require a delay between the host boot and the booting of the first VM,
+see the section on xref:first_guest_boot_delay[Proxmox VE Node Management].
+
+
+[[qm_qemu_agent]]
+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
+agent.
+
+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
+https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/virtio-win.iso[Fedora
+VirtIO driver ISO].
+
+[[qm_qga_enable]]
+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
+effect.
+
+[[qm_qga_auto_trim]]
+Automatic TRIM Using QGA
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+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.
+
+NOTE: There is a caveat with ext4 on Linux, because it uses an in-memory
+optimization to avoid issuing duplicate TRIM requests. Since the guest doesn't
+know about the change in the underlying storage, only the first guest-trim will
+run as expected. Subsequent ones, until the next reboot, will only consider
+parts of the filesystem that changed since then.
+
+[[qm_qga_fsfreeze]]
+Filesystem Freeze & Thaw on Backup
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+By default, guest filesystems are synced via the 'fs-freeze' QEMU Guest Agent
+Command when a backup is performed, to provide consistency.
+
+On Windows guests, some applications might handle consistent backups themselves
+by hooking into the Windows VSS (Volume Shadow Copy Service) layer, a
+'fs-freeze' then might interfere with that. For example, it has been observed
+that calling 'fs-freeze' with some SQL Servers triggers VSS to call the SQL
+Writer VSS module in a mode that breaks the SQL Server backup chain for
+differential backups.
+
+For such setups you can configure {pve} to not issue a freeze-and-thaw cycle on
+backup by setting the `freeze-fs-on-backup` QGA option to `0`. This can also be
+done via the GUI with the 'Freeze/thaw guest filesystems on backup for
+consistency' option.
+
+IMPORTANT: Disabling this option can potentially lead to backups with inconsistent
+filesystems and should therefore only be disabled if you know what you are
+doing.
+
+Troubleshooting
+^^^^^^^^^^^^^^^
+
+.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.
+
+[[qm_spice_enhancements]]
+SPICE Enhancements
+~~~~~~~~~~~~~~~~~~
+
+SPICE Enhancements are optional features that can improve the remote viewer
+experience.
+
+To enable them via the GUI go to the *Options* panel of the virtual machine. Run
+the following command to enable them via the CLI:
+
+----
+qm set <vmid> -spice_enhancements foldersharing=1,videostreaming=all
+----
+
+NOTE: To use these features the <<qm_display,*Display*>> of the virtual machine
+must be set to SPICE (qxl).
+
+Folder Sharing
+^^^^^^^^^^^^^^
+
+Share a local folder with the guest. The `spice-webdavd` daemon needs to be
+installed in the guest. It makes the shared folder available through a local
+WebDAV server located at http://localhost:9843.
+
+For Windows guests the installer for the 'Spice WebDAV daemon' can be downloaded
+from the
+https://www.spice-space.org/download.html#windows-binaries[official SPICE website].
+
+Most Linux distributions have a package called `spice-webdavd` that can be
+installed.
+
+To share a folder in Virt-Viewer (Remote Viewer) go to 'File -> Preferences'.
+Select the folder to share and then enable the checkbox.
+
+NOTE: Folder sharing currently only works in the Linux version of Virt-Viewer.
+
+CAUTION: Experimental! Currently this feature does not work reliably.
+
+Video Streaming
+^^^^^^^^^^^^^^^
+
+Fast refreshing areas are encoded into a video stream. Two options exist:
+
+* *all*: Any fast refreshing area will be encoded into a video stream.
+* *filter*: Additional filters are used to decide if video streaming should be
+ used (currently only small window surfaces are skipped).
+
+A general recommendation if video streaming should be enabled and which option
+to choose from cannot be given. Your mileage may vary depending on the specific
+circumstances.
+
+Troubleshooting
+^^^^^^^^^^^^^^^
+
+.Shared folder does not show up
+
+Make sure the WebDAV service is enabled and running in the guest. On Windows it
+is called 'Spice webdav proxy'. In Linux the name is 'spice-webdavd' but can be
+different depending on the distribution.
+
+If the service is running, check the WebDAV server by opening
+http://localhost:9843 in a browser in the guest.
+
+It can help to restart the SPICE session.