Fixed some typos and slight language improvements

[pve-docs.git] / vzdump.adoc

diff --git a/vzdump.adoc b/vzdump.adoc
index 00f4aa67a2aaf9b6c0cd236fef2677fd753c021a..fb1ac3d0c3c9853a51aa0ce9ffb9e0ebed3b01a2 100644 (file)
--- a/vzdump.adoc
+++ b/vzdump.adoc
@@ -1,7 +1,8 @@
+[[chapter_vzdump]]

 ifdef::manvolnum[]
 ifdef::manvolnum[]

-PVE({manvolnum})
-================
-include::attributes.txt[]
+vzdump(1)
+=========
+:pve-toplevel:

 
 NAME
 ----
 
 NAME
 ----


@@ -9,7 +10,7 @@ NAME
 vzdump - Backup Utility for VMs and Containers 
 
 
 vzdump - Backup Utility for VMs and Containers 
 
 

-SYNOPSYS
+SYNOPSIS

 --------
 
 include::vzdump.1-synopsis.adoc[]
 --------
 
 include::vzdump.1-synopsis.adoc[]


@@ -18,68 +19,103 @@ include::vzdump.1-synopsis.adoc[]
 DESCRIPTION
 -----------
 endif::manvolnum[]
 DESCRIPTION
 -----------
 endif::manvolnum[]

-

 ifndef::manvolnum[]
 Backup and Restore
 ==================
 ifndef::manvolnum[]
 Backup and Restore
 ==================

-include::attributes.txt[]
+:pve-toplevel:

 endif::manvolnum[]
 
 endif::manvolnum[]
 

-'vzdump' is a utility to make consistent backups of running guest
-systems. It basically creates an archive of the guest private area,
-which also includes the guest configuration files. 'vzdump' currently
-supports LXC containers and QemuServer VMs. There are several ways to
-provide consistency (option `mode`), depending on the guest type.
+Backups are a requirement 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.
+
+{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
+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
+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 `mode` for VMs:
+Backup modes
+------------
+
+There are several ways to provide consistency (option `mode`), 
+depending on the guest type.
+
+.Backup modes for VMs:

 
 `stop` mode::
 
 
 `stop` mode::
 

-This first performns a clean shutdown of the VM to make sure it is
-stopped. It then starts the VM in suspended mode and uses the qemu
-backup feature to dump all data. If the VM was running, we start
-(resume) it immediately after starting the qemu backup task. This
-keeps the downtime as low as possible.
+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
+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.

 
 `suspend` mode::
 
 
 `suspend` mode::
 

-This mode does not really make sense for qemu. Please use snapshot
-mode 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::
 
 
 `snapshot` mode::
 

-This mode simply starts a qemu live backup task. If the guest agent
-is enabled (`agent: 1`) and running, it calls 'guest-fsfreeze-freeze'
-and 'guest-fsfreeze-thaw' to improve consistency.
+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
 
 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].
+https://git.proxmox.com/?p=pve-qemu.git;a=blob_plain;f=backup.txt[here].

 
 

-NOTE: Qemu backup provides snapshots on any storage type. It does
-not require that the underlying storage supports snapshots.
+NOTE: Proxmox VE 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.
+However the VM itself is not booted, only its disk(s) are read.

 
 

-
-.Backup `mode` for Containers:
+.Backup modes for Containers:

 
 `stop` mode::
 
 
 `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
 
 `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 file system and the target storage of
+the backup is an NFS/CIFS server, you should set `--tmpdir` to reside on a
+local file system 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::
 
 
 `snapshot` mode::
 


@@ -90,12 +126,14 @@ snapshot content will be archived in a tar file. Finally, the temporary
 snapshot is deleted again.
 
 NOTE: `snapshot` mode requires that all backed up volumes are on a storage that
 snapshot is deleted again.
 
 NOTE: `snapshot` mode requires that all backed up volumes are on a storage that

-supports snapshots. Using the `backup=no` mountpoint option individual volumes
+supports snapshots. Using the `backup=no` mount point option individual volumes

 can be excluded from the backup (and thus this requirement).
 
 can be excluded from the backup (and thus this requirement).
 

-NOTE: bind and device mountpoints are skipped during backup operations, like
-volume mountpoints with the backup option disabled.
-
+// see PVE::VZDump::LXC::prepare()
+NOTE: By default additional mount points besides the Root Disk mount point are
+not included in backups. For volume mount points you can set the *Backup* option
+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.

 
 Backup File Names
 -----------------
 
 Backup File Names
 -----------------


@@ -109,28 +147,73 @@ That way it is possible to store several backup in the same
 directory. The parameter `maxfiles` can be used to specify the
 maximum number of backups to keep.
 
 directory. The parameter `maxfiles` can be used to specify the
 maximum number of backups to keep.
 

+[[vzdump_restore]]

 Restore
 -------
 
 Restore
 -------
 

-The resulting archive files can be restored with the following programs.
+A backup archive can be restored through the {pve} web GUI or through the
+following CLI tools:

 
 
 `pct restore`:: Container restore utility
 
 
 
 `pct restore`:: Container restore utility
 

-`qmrestore`:: QemuServer restore utility
+`qmrestore`:: Virtual Machine restore utility

 
 For details see the corresponding manual pages.
 
 
 For details see the corresponding manual pages.
 

+Bandwidth Limit
+~~~~~~~~~~~~~~~
+
+Restoring one or more big backups may need a lot of resources, especially
+storage bandwidth for both reading from the backup storage and writing to
+the target storage. This can negatively effect other virtual guest as access
+to storage can get congested.
+
+To avoid this you can set bandwidth limits for a backup job. {pve}
+implements two kinds of limits for restoring and archive:
+
+* per-restore limit: denotes the maximal amount of bandwidth for
+  reading from a backup archive
+
+* per-storage write limit: denotes the maximal amount of bandwidth used for
+  writing to a specific storage
+
+The read limit indirectly affects the write limit, as we cannot write more
+than we read. A smaller per-job limit will overwrite a bigger per-storage
+limit. A bigger per-job limit will only overwrite the per-storage limit if
+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
+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
+does not impact their operations.
+
+NOTE: You can use `0` for the `bwlimit` parameter to disable all limits for
+a specific restore job. This can be helpful if you need to restore a very
+important virtual guest as fast as possible. (Needs `Data.Allocate'
+permissions on storage)
+
+Most times your storage's generally available bandwidth stays the same over
+time, thus we implemented the possibility to set a default bandwidth limit
+per configured storage, this can be done with:
+
+----
+# pvesm set STORAGEID --bwlimit KIBs
+----
+
+

 Configuration
 -------------
 
 Configuration
 -------------
 

-Global configuration is stored in '/etc/vzdump.conf'. The file uses a
+Global configuration is stored in `/etc/vzdump.conf`. The file uses a

 simple colon separated key/value format. Each line has the following
 format:
 
  OPTION: value
 
 simple colon separated key/value format. Each line has the following
 format:
 
  OPTION: value
 

-Blank lines in the file are ignored, and lines starting with a '#'
+Blank lines in the file are ignored, and lines starting with a `#`

 character are treated as comments and are also ignored. Values from
 this file are used as default, and can be overwritten on the command
 line.
 character are treated as comments and are also ignored. Values from
 this file are used as default, and can be overwritten on the command
 line.


@@ -140,7 +223,7 @@ We currently support the following options:
 include::vzdump.conf.5-opts.adoc[]
 
 
 include::vzdump.conf.5-opts.adoc[]
 
 

-.Example 'vzdump.conf' Configuration
+.Example `vzdump.conf` Configuration

 ----
 tmpdir: /mnt/fast_local_disk
 storage: my_backup_storage
 ----
 tmpdir: /mnt/fast_local_disk
 storage: my_backup_storage


@@ -154,17 +237,16 @@ Hook Scripts
 You can specify a hook script with option `--script`. This script is
 called at various phases of the backup process, with parameters
 accordingly set. You can find an example in the documentation
 You can specify a hook script with option `--script`. This script is
 called at various phases of the backup process, with parameters
 accordingly set. You can find an example in the documentation

-directory ('vzdump-hook-script.pl').
+directory (`vzdump-hook-script.pl`).

 
 File Exclusions
 ---------------
 
 NOTE: this option is only available for container backups.
 
 
 File Exclusions
 ---------------
 
 NOTE: this option is only available for container backups.
 

-'vzdump' skips the following files by default (disable with the option
+`vzdump` skips the following files by default (disable with the option

 `--stdexcludes 0`)
 
 `--stdexcludes 0`)
 

- /var/log/?*

  /tmp/?*
  /var/tmp/?*
  /var/run/?*pid
  /tmp/?*
  /var/tmp/?*
  /var/run/?*pid


@@ -183,7 +265,7 @@ Examples
 
 Simply dump guest 777 - no snapshot, just archive the guest private area and
 configuration files to the default dump directory (usually
 
 Simply dump guest 777 - no snapshot, just archive the guest private area and
 configuration files to the default dump directory (usually

-'/var/lib/vz/dump/').
+`/var/lib/vz/dump/`).

 
  # vzdump 777
 
 
  # vzdump 777