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Dietmar Maurer 2016-09-06 06:24:13 +02:00
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@ -26,86 +26,92 @@ include::attributes.txt[]
endif::manvolnum[]
Backups are a requirements for any sensible IT deployment, and {pve}
provides a fully integrated solution, using the capabilities of each storage
and each guest system type. This allows the system administrator to fine tune via
the `mode` option between consistency of the backups and downtime of the guest
system. Proxmox VE 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.
provides a fully integrated solution, using the capabilities of each
storage and each guest system type. This allows the system
administrator to fine tune via the `mode` option between consistency
of the backups and downtime of the guest system.
{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.
.Backup Storage
Before a backup can run, a backup storage must be defined.
Refer to the Storage documentation on how to add a storage. A backup storage
Before a backup can run, a backup storage must be defined. Refer to
the Storage documentation on how to add a storage. A backup storage
must be a file level storage, as backups are stored as regular files.
In most situations, using a NFS server is a good way to store backups.
You can save those backups later to a tape drive, for off-site archive.
You can save those backups later to a tape drive, for off-site
archiving.
.Scheduled Backup
Backup jobs can be scheduled so that they are executed automatically on
specific days and times, for selectable nodes and guest systems.
Configuration of scheduled backups is done at the Datacenter level in the GUI,
which will generate a cron entry in /etc/cron.d/vzdump.
Backup jobs can be scheduled so that they are executed automatically
on specific days and times, for selectable nodes and guest systems.
Configuration of scheduled backups is done at the Datacenter level in
the GUI, which will generate a cron entry in /etc/cron.d/vzdump.
Backup modes
------------
There are several ways to provide consistency (option `mode`),
depending on the guest type.
.Backup modes for VMs:
`stop` mode::
This mode provides the highest consistency of the backup, at the
cost of a downtime in the VM operation.
It works by executing an orderly shutdown of the VM, and then runs a background
Qemu process to backup the VM data. After the backup is complete, the
Qemu process resumes the VM to full operation mode if it was previously running.
This mode provides the highest consistency of the backup, at the cost
of a downtime in the VM operation. It works by executing an orderly
shutdown of the VM, and then runs a background Qemu process to backup
the VM data. After the backup is complete, the Qemu process resumes
the VM to full operation mode if it was previously running.
`suspend` mode::
This mode is provided for compatibility reason, and suspends the VM before
calling the `snapshot` mode. Since suspending the VM results in a longer
downtime and does not necessarily improve the data consistency,
the use of the `snapshot` mode is recommended instead.
This mode is provided for compatibility reason, and suspends the VM
before calling the `snapshot` mode. Since suspending the VM results in
a longer downtime and does not necessarily improve the data
consistency, the use of the `snapshot` mode is recommended instead.
`snapshot` mode::
This mode provides the lowest operation downtime, at the cost of a small
inconstancy risk.
It works by performing a Proxmox VE live backup, in which data blocks are copy
while the VM is running. If the guest agent is enabled (`agent: 1`) and running,
it calls 'guest-fsfreeze-freeze' and 'guest-fsfreeze-thaw' to improve
This mode provides the lowest operation downtime, at the cost of a
small inconstancy risk. It works by performing a Proxmox VE live
backup, in which data blocks are copied while the VM is running. If the
guest agent is enabled (`agent: 1`) and running, it calls
'guest-fsfreeze-freeze' and 'guest-fsfreeze-thaw' to improve
consistency.
A technical overview of the Proxmox VE live backup for QemuServer can
be found online
https://git.proxmox.com/?p=pve-qemu-kvm.git;a=blob;f=backup.txt[here].
NOTE: For VMs, this _snapshot_ mode relates to the fact that the backup is
performed while the VM is running. This has here nothing to do with file systems
snapshots and can be operated on any kind of storage.
NOTE: Proxmox VE live backup provides snapshot-like semantics on any
storage type. It does not require that the underlying storage supports
snapshots.
.Backup modes for Containers:
`stop` mode::
Stop the container for the duration of the backup. This potentially results in
a very long downtime.
Stop the container for the duration of the backup. This potentially
results in a very long downtime.
`suspend` mode::
This mode uses rsync to copy the container data to a temporary
location (see option `--tmpdir`). Then the container is suspended and a second
rsync copies changed files. After that, the container is started (resumed)
again. This results in minimal downtime, but needs additional space
to hold the container copy.
location (see option `--tmpdir`). Then the container is suspended and
a second rsync copies changed files. After that, the container is
started (resumed) again. This results in minimal downtime, but needs
additional space to hold the container copy.
+
When the container is on a local filesystem and the target storage of the backup
is an NFS server, you should set `--tmpdir` to reside on a local filesystem too,
as this will result in a many fold performance improvement.
Use of a local `tmpdir` is also required if you want to backup a local container
using ACLs in suspend mode if the backup storage is an NFS server.
When the container is on a local filesystem and the target storage of
the backup is an NFS server, you should set `--tmpdir` to reside on a
local filesystem too, as this will result in a many fold performance
improvement. Use of a local `tmpdir` is also required if you want to
backup a local container using ACLs in suspend mode if the backup
storage is an NFS server.
`snapshot` mode::