From 94e50bf6cc95fd6ba48dd6ed4a455989c103cc75 Mon Sep 17 00:00:00 2001 From: Dietmar Maurer Date: Tue, 6 Sep 2016 06:24:13 +0200 Subject: [PATCH] revert live backup note, white space cleanups --- vzdump.adoc | 88 ++++++++++++++++++++++++++++------------------------- 1 file changed, 47 insertions(+), 41 deletions(-) diff --git a/vzdump.adoc b/vzdump.adoc index a2eec20..5341200 100644 --- a/vzdump.adoc +++ b/vzdump.adoc @@ -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::