X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=vzdump.adoc;h=1c396804f0cf9b08c8d8bc44231d4a760778acc6;hb=921926036a9bb3824833ca705e68a45a66f38f09;hp=97bdcf2efae4132516e230c9e1402333d2369a75;hpb=49a5e11cd14742d8ad28116fab7fce9fc85321bd;p=pve-docs.git diff --git a/vzdump.adoc b/vzdump.adoc index 97bdcf2..1c39680 100644 --- a/vzdump.adoc +++ b/vzdump.adoc @@ -1,7 +1,8 @@ +[[chapter_vzdump]] ifdef::manvolnum[] -PVE({manvolnum}) -================ -include::attributes.txt[] +vzdump(1) +========= +:pve-toplevel: NAME ---- @@ -18,14 +19,13 @@ include::vzdump.1-synopsis.adoc[] DESCRIPTION ----------- endif::manvolnum[] - ifndef::manvolnum[] Backup and Restore ================== -include::attributes.txt[] +:pve-toplevel: endif::manvolnum[] -Backups are a requirements for any sensible IT deployment, and {pve} +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 @@ -62,10 +62,11 @@ depending on the guest type. `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. +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:: @@ -77,19 +78,22 @@ 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 +small inconsistency risk. It works by performing a {pve} 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 +A technical overview of the {pve} 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: Proxmox VE live backup provides snapshot-like semantics on any +NOTE: {pve} live backup provides snapshot-like semantics on any storage type. It does not require that the underlying storage supports -snapshots. +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 modes for Containers: @@ -107,7 +111,7 @@ started (resumed) again. This results in minimal downtime, but needs additional space to hold the container copy. + When the container is on a local file system and the target storage of -the backup is an NFS server, you should set `--tmpdir` to reside on a +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 @@ -125,9 +129,11 @@ NOTE: `snapshot` mode requires that all backed up volumes are on a storage that supports snapshots. Using the `backup=no` mount point option individual volumes can be excluded from the backup (and thus this requirement). -NOTE: bind and device mount points are skipped during backup operations, like -volume mount points 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 ----------------- @@ -141,18 +147,96 @@ 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. +Backup File Compression +----------------------- + +The backup file can be compressed with one of the following algorithms: `lzo` +footnote:[Lempel–Ziv–Oberhumer a lossless data compression algorithm +https://en.wikipedia.org/wiki/Lempel-Ziv-Oberhumer], `gzip` footnote:[gzip - +based on the DEFLATE algorithm https://en.wikipedia.org/wiki/Gzip] or `zstd` +footnote:[Zstandard a lossless data compression algorithm +https://en.wikipedia.org/wiki/Zstandard]. + +Currently, Zstandard (zstd) is the fastest of these three algorithms. +Multi-threading is another advantage of zstd over lzo and gzip. Lzo and gzip +are more widely used and often installed by default. + +You can install pigz footnote:[pigz - parallel implementation of gzip +https://zlib.net/pigz/] as a drop-in replacement for gzip to provide better +performance due to multi-threading. For pigz & zstd, the amount of +threads/cores can be adjusted. See the +xref:vzdump_configuration[configuration options] below. + +The extension of the backup file name can usually be used to determine which +compression algorithm has been used to create the backup. + +|=== +|.zst | Zstandard (zstd) compression +|.gz or .tgz | gzip compression +|.lzo | lzo compression +|=== + +If the backup file name doesn't end with one of the above file extensions, then +it was not compressed by vzdump. + + +[[vzdump_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 -`qmrestore`:: QemuServer restore utility +`qmrestore`:: Virtual Machine restore utility 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 affect other virtual guests 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 ` 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 restore=KIBs +---- + +[[vzdump_configuration]] Configuration -------------