{pve} backups are always full backups - containing the VM/CT
configuration and all data. Backups can be started via the GUI or via
-the `vzdump` command line tool.
+the `vzdump` command-line tool.
.Backup Storage
This mode provides the highest consistency of the backup, at the cost
of a short downtime in the VM operation. It works by executing an
-orderly shutdown of the VM, and then runs a background Qemu process to
+orderly shutdown of the VM, and then runs a background QEMU process to
backup the VM data. After the backup is started, the VM goes to full
operation mode if it was previously running. Consistency is guaranteed
by using the live backup feature.
NOTE: {pve} live backup provides snapshot-like semantics on any
storage type. It does not require that the underlying storage supports
snapshots. Also please note that since the backups are done via
-a background Qemu process, a stopped VM will appear as running for a
-short amount of time while the VM disks are being read by Qemu.
+a background QEMU process, a stopped VM will appear as running for a
+short amount of time while the VM disks are being read by QEMU.
However the VM itself is not booted, only its disk(s) are read.
.Backup modes for Containers:
to include the mount point in the backup. Device and bind mounts are never
backed up as their content is managed outside the {pve} storage library.
+VM Backup Fleecing
+~~~~~~~~~~~~~~~~~~
+
+When a backup for a VM is started, QEMU will install a "copy-before-write"
+filter in its block layer. This filter ensures that upon new guest writes, old
+data still needed for the backup is sent to the backup target first. The guest
+write blocks until this operation is finished so guest IO to not-yet-backed-up
+sectors will be limited by the speed of the backup target.
+
+With backup fleecing, such old data is cached in a fleecing image rather than
+sent directly to the backup target. This can help guest IO performance and even
+prevent hangs in certain scenarios, at the cost of requiring more storage space.
+Use e.g. `vzdump 123 --fleecing enabled=1,storage=local-lvm` to enable backup
+fleecing, with fleecing images created on the storage `local-lvm`.
+
+The fleecing storage should be a fast local storage, with thin provisioning and
+discard support. Examples are LVM-thin, RBD, ZFS with `sparse 1` in the storage
+configuration, many file-based storages. Ideally, the fleecing storage is a
+dedicated storage, so it running full will not affect other guests and just fail
+the backup. Parts of the fleecing image that have been backed up will be
+discarded to try and keep the space usage low.
+
+For file-based storages that do not support discard (e.g. NFS before version
+4.2), you should set `preallocation off` in the storage configuration. In
+combination with `qcow2` (used automatically as the format for the fleecing
+image when the storage supports it), this has the advantage that already
+allocated parts of the image can be re-used later, which can still help save
+quite a bit of space.
+
+WARNING: On a storage that's not thinly provisioned, e.g. LVM or ZFS without the
+`sparse` option, the full size of the original disk needs to be reserved for the
+fleecing image up-front. On a thinly provisioned storage, the fleecing image can
+grow to the same size as the original image only if the guest re-writes a whole
+disk while the backup is busy with another disk.
+
Backup File Names
-----------------
Backup Jobs
-----------
+[thumbnail="screenshot/gui-cluster-backup-overview.png"]
+
Besides triggering a backup manually, you can also setup periodic jobs that
backup all, or a selection of virtual guest to a storage. You can manage the
jobs in the UI under 'Datacenter' -> 'Backup' or via the `/cluster/backup` API
endpoint. Both will generate job entries in `/etc/pve/jobs.cfg`, which are
parsed and executed by the `pvescheduler` daemon.
+[thumbnail="screenshot/gui-cluster-backup-edit-01-general.png", float="left"]
+
A job is either configured for all cluster nodes or a specific node, and is
executed according to a given schedule. The format for the schedule is very
similar to `systemd` calendar events, see the
Since scheduled backups miss their execution when the host was offline or the
pvescheduler was disabled during the scheduled time, it is possible to configure
-the behaviour for catching up. By enabling the `Repeat missed` option
-(`repeat-missed` in the config), you can tell the scheduler that it should run
-missed jobs as soon as possible.
-
-There are a few settings for tuning backup performance not exposed in the UI.
-The most notable is `bwlimit` for limiting IO bandwidth. The amount of threads
-used for the compressor can be controlled with the `pigz` (replacing `gzip`),
-respectively, `zstd` setting. Furthermore, there is `ionice`. See the
+the behaviour for catching up. By enabling the `Repeat missed` option (in the
+'Advanced' tab in the UI, `repeat-missed` in the config), you can tell the
+scheduler that it should run missed jobs as soon as possible.
+
+[thumbnail="screenshot/gui-cluster-backup-edit-04-advanced.png"]
+
+There are a few settings for tuning backup performance (some of which are
+exposed in the 'Advanced' tab in the UI). The most notable is `bwlimit` for
+limiting IO bandwidth. The amount of threads used for the compressor can be
+controlled with the `pigz` (replacing `gzip`), respectively, `zstd` setting.
+Furthermore, there are `ionice` (when the BFQ scheduler is used) and, as part of
+the `performance` setting, `max-workers` (affects VM backups only) and
+`pbs-entries-max` (affects container backups only). See the
xref:vzdump_configuration[configuration options] for details.
[[vzdump_retention]]
----------------
With the `prune-backups` option you can specify which backups you want to keep
-in a flexible manner. The following retention options are available:
+in a flexible manner.
+
+[thumbnail="screenshot/gui-cluster-backup-edit-02-retention.png"]
+
+The following retention options are available:
`keep-all <boolean>` ::
Keep all backups. If this is `true`, no other options can be set.
You can add notes to backups using the 'Edit Notes' button in the UI or via the
storage content API.
+[thumbnail="screenshot/gui-cluster-backup-edit-03-template.png"]
+
It is also possible to specify a template for generating notes dynamically for
a backup job and for manual backup. The template string can contain variables,
surrounded by two curly braces, which will be replaced by the corresponding
you have `Data.Allocate' permissions on the affected storage.
You can use the `--bwlimit <integer>` option from the restore CLI commands
-to set up a restore job specific bandwidth limit. Kibit/s is used as unit
+to set up a restore job specific bandwidth limit. KiB/s is used as unit
for the limit, this means passing `10240' will limit the read speed of the
backup to 10 MiB/s, ensuring that the rest of the possible storage bandwidth
is available for the already running virtual guests, and thus the backup
hypervisor system to danger. The VM will stop itself after a timeout. This
entire process happens transparently from a user's point of view.
+NOTE: For troubleshooting purposes, each temporary VM instance generates a log
+file in `/var/log/proxmox-backup/file-restore/`. The log file might contain
+additional information in case an attempt to restore individual files or
+accessing file systems contained in a backup archive fails.
+
[[vzdump_configuration]]
Configuration
-------------
# vzdump 777 --mode suspend
Backup all guest systems and send notification mails to root and admin.
+Due to `mailto` being set and `notification-mode` being set to `auto` by
+default, the notification mails are sent via the system's `sendmail`
+command instead of the notification system.
# vzdump --all --mode suspend --mailto root --mailto admin
ifdef::manvolnum[]
include::pve-copyright.adoc[]
endif::manvolnum[]
-
projects / pve-docs.git / blobdiff