vzdump: add section about backup fleecing

[pve-docs.git] / pvesm.adoc

[[chapter_storage]]
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pvesm(1)
========
:pve-toplevel:

NAME
----

pvesm - Proxmox VE Storage Manager


SYNOPSIS
--------

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

DESCRIPTION
-----------
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{pve} Storage
=============
:pve-toplevel:
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:title: Storage
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The {pve} storage model is very flexible. Virtual machine images
can either be stored on one or several local storages, or on shared
storage like NFS or iSCSI (NAS, SAN). There are no limits, and you may
configure as many storage pools as you like. You can use all
storage technologies available for Debian Linux.

One major benefit of storing VMs on shared storage is the ability to
live-migrate running machines without any downtime, as all nodes in
the cluster have direct access to VM disk images. There is no need to
copy VM image data, so live migration is very fast in that case.

The storage library (package `libpve-storage-perl`) uses a flexible
plugin system to provide a common interface to all storage types. This
can be easily adopted to include further storage types in the future.


Storage Types
-------------

There are basically two different classes of storage types:

File level storage::

File level based storage technologies allow access to a fully featured (POSIX)
file system.  They are in general more flexible than any Block level storage
(see below), and allow you to store content of any type. ZFS is probably the
most advanced system, and it has full support for snapshots and clones.

Block level storage::

Allows to store large 'raw' images. It is usually not possible to store
other files (ISO, backups, ..) on such storage types. Most modern
block level storage implementations support snapshots and clones.
RADOS and GlusterFS are distributed systems, replicating storage
data to different nodes.


.Available storage types
[width="100%",cols="<2d,1*m,4*d",options="header"]
|===========================================================
|Description    |Plugin type |Level  |Shared|Snapshots|Stable
|ZFS (local)    |zfspool     |both^1^|no    |yes      |yes
|Directory      |dir         |file   |no    |no^2^    |yes
|BTRFS          |btrfs       |file   |no    |yes      |technology preview
|NFS            |nfs         |file   |yes   |no^2^    |yes
|CIFS           |cifs        |file   |yes   |no^2^    |yes
|Proxmox Backup |pbs         |both   |yes   |n/a      |yes
|GlusterFS      |glusterfs   |file   |yes   |no^2^    |yes
|CephFS         |cephfs      |file   |yes   |yes      |yes
|LVM            |lvm         |block  |no^3^ |no       |yes
|LVM-thin       |lvmthin     |block  |no    |yes      |yes
|iSCSI/kernel   |iscsi       |block  |yes   |no       |yes
|iSCSI/libiscsi |iscsidirect |block  |yes   |no       |yes
|Ceph/RBD       |rbd         |block  |yes   |yes      |yes
|ZFS over iSCSI |zfs         |block  |yes   |yes      |yes
|===========================================================

^1^: Disk images for VMs are stored in ZFS volume (zvol) datasets, which provide
block device functionality.

^2^: On file based storages, snapshots are possible with the 'qcow2' format.

^3^: It is possible to use LVM on top of an iSCSI or FC-based storage.
That way you get a `shared` LVM storage


Thin Provisioning
~~~~~~~~~~~~~~~~~

A number of storages, and the QEMU image format `qcow2`, support 'thin
provisioning'.  With thin provisioning activated, only the blocks that
the guest system actually use will be written to the storage.

Say for instance you create a VM with a 32GB hard disk, and after
installing the guest system OS, the root file system of the VM contains
3 GB of data.  In that case only 3GB are written to the storage, even
if the guest VM sees a 32GB hard drive. In this way thin provisioning
allows you to create disk images which are larger than the currently
available storage blocks. You can create large disk images for your
VMs, and when the need arises, add more disks to your storage without
resizing the VMs' file systems.

All storage types which have the ``Snapshots'' feature also support thin
provisioning.

CAUTION: If a storage runs full, all guests using volumes on that
storage receive IO errors. This can cause file system inconsistencies
and may corrupt your data. So it is advisable to avoid
over-provisioning of your storage resources, or carefully observe
free space to avoid such conditions.


Storage Configuration
---------------------

All {pve} related storage configuration is stored within a single text
file at `/etc/pve/storage.cfg`. As this file is within `/etc/pve/`, it
gets automatically distributed to all cluster nodes. So all nodes
share the same storage configuration.

Sharing storage configuration makes perfect sense for shared storage,
because the same ``shared'' storage is accessible from all nodes. But it is
also useful for local storage types. In this case such local storage
is available on all nodes, but it is physically different and can have
totally different content.


Storage Pools
~~~~~~~~~~~~~

Each storage pool has a `<type>`, and is uniquely identified by its
`<STORAGE_ID>`. A pool configuration looks like this:

----
<type>: <STORAGE_ID>
	<property> <value>
	<property> <value>
	<property>
	...
----

The `<type>: <STORAGE_ID>` line starts the pool definition, which is then
followed by a list of properties. Most properties require a value. Some have
reasonable defaults, in which case you can omit the value.

To be more specific, take a look at the default storage configuration
after installation. It contains one special local storage pool named
`local`, which refers to the directory `/var/lib/vz` and is always
available. The {pve} installer creates additional storage entries
depending on the storage type chosen at installation time.

.Default storage configuration (`/etc/pve/storage.cfg`)
----
dir: local
	path /var/lib/vz
	content iso,vztmpl,backup

# default image store on LVM based installation
lvmthin: local-lvm
	thinpool data
	vgname pve
	content rootdir,images

# default image store on ZFS based installation
zfspool: local-zfs
	pool rpool/data
	sparse
	content images,rootdir
----

CAUTION: It is problematic to have multiple storage configurations pointing to
the exact same underlying storage. Such an _aliased_ storage configuration can
lead to two different volume IDs ('volid') pointing to the exact same disk
image. {pve} expects that the images' volume IDs point to, are unique. Choosing
different content types for _aliased_ storage configurations can be fine, but
is not recommended.

Common Storage Properties
~~~~~~~~~~~~~~~~~~~~~~~~~

A few storage properties are common among different storage types.

nodes::

List of cluster node names where this storage is
usable/accessible. One can use this property to restrict storage
access to a limited set of nodes.

content::

A storage can support several content types, for example virtual disk
images, cdrom iso images, container templates or container root
directories. Not all storage types support all content types. One can set
this property to select what this storage is used for.

images:::

QEMU/KVM VM images.

rootdir:::

Allow to store container data.

vztmpl:::

Container templates.

backup:::

Backup files (`vzdump`).

iso:::

ISO images

snippets:::

Snippet files, for example guest hook scripts

shared::

Indicate that this is a single storage with the same contents on all nodes (or
all listed in the 'nodes' option). It will not make the contents of a local
storage automatically accessible to other nodes, it just marks an already shared
storage as such!

disable::

You can use this flag to disable the storage completely.

maxfiles::

Deprecated, please use `prune-backups` instead. Maximum number of backup files
per VM. Use `0` for unlimited.

prune-backups::

Retention options for backups. For details, see
xref:vzdump_retention[Backup Retention].

format::

Default image format (`raw|qcow2|vmdk`)

preallocation::

Preallocation mode (`off|metadata|falloc|full`) for `raw` and `qcow2` images on
file-based storages. The default is `metadata`, which is treated like `off` for
`raw` images. When using network storages in combination with large `qcow2`
images, using `off` can help to avoid timeouts.

WARNING: It is not advisable to use the same storage pool on different
{pve} clusters. Some storage operation need exclusive access to the
storage, so proper locking is required. While this is implemented
within a cluster, it does not work between different clusters.


Volumes
-------

We use a special notation to address storage data. When you allocate
data from a storage pool, it returns such a volume identifier. A volume
is identified by the `<STORAGE_ID>`, followed by a storage type
dependent volume name, separated by colon. A valid `<VOLUME_ID>` looks
like:

 local:230/example-image.raw

 local:iso/debian-501-amd64-netinst.iso

 local:vztmpl/debian-5.0-joomla_1.5.9-1_i386.tar.gz

 iscsi-storage:0.0.2.scsi-14f504e46494c4500494b5042546d2d646744372d31616d61

To get the file system path for a `<VOLUME_ID>` use:

 pvesm path <VOLUME_ID>


Volume Ownership
~~~~~~~~~~~~~~~~

There exists an ownership relation for `image` type volumes. Each such
volume is owned by a VM or Container. For example volume
`local:230/example-image.raw` is owned by VM 230. Most storage
backends encodes this ownership information into the volume name.

When you remove a VM or Container, the system also removes all
associated volumes which are owned by that VM or Container.


Using the Command-line Interface
--------------------------------

It is recommended to familiarize yourself with the concept behind storage
pools and volume identifiers, but in real life, you are not forced to do any
of those low level operations on the command line. Normally,
allocation and removal of volumes is done by the VM and Container
management tools.

Nevertheless, there is a command-line tool called `pvesm` (``{pve}
Storage Manager''), which is able to perform common storage management
tasks.


Examples
~~~~~~~~

Add storage pools

 pvesm add <TYPE> <STORAGE_ID> <OPTIONS>
 pvesm add dir <STORAGE_ID> --path <PATH>
 pvesm add nfs <STORAGE_ID> --path <PATH> --server <SERVER> --export <EXPORT>
 pvesm add lvm <STORAGE_ID> --vgname <VGNAME>
 pvesm add iscsi <STORAGE_ID> --portal <HOST[:PORT]> --target <TARGET>

Disable storage pools

 pvesm set <STORAGE_ID> --disable 1

Enable storage pools

 pvesm set <STORAGE_ID> --disable 0

Change/set storage options

 pvesm set <STORAGE_ID> <OPTIONS>
 pvesm set <STORAGE_ID> --shared 1
 pvesm set local --format qcow2
 pvesm set <STORAGE_ID> --content iso

Remove storage pools. This does not delete any data, and does not
disconnect or unmount anything. It just removes the storage
configuration.

 pvesm remove <STORAGE_ID>

Allocate volumes

 pvesm alloc <STORAGE_ID> <VMID> <name> <size> [--format <raw|qcow2>]

Allocate a 4G volume in local storage. The name is auto-generated if
you pass an empty string as `<name>`

 pvesm alloc local <VMID> '' 4G

Free volumes

 pvesm free <VOLUME_ID>

WARNING: This really destroys all volume data.

List storage status

 pvesm status

List storage contents

 pvesm list <STORAGE_ID> [--vmid <VMID>]

List volumes allocated by VMID

 pvesm list <STORAGE_ID> --vmid <VMID>

List iso images

 pvesm list <STORAGE_ID> --content iso

List container templates

 pvesm list <STORAGE_ID> --content vztmpl

Show file system path for a volume

 pvesm path <VOLUME_ID>

Exporting the volume `local:103/vm-103-disk-0.qcow2` to the file `target`.
This is mostly used internally with `pvesm import`.
The stream format qcow2+size is different to the qcow2 format.
Consequently, the exported file cannot simply be attached to a VM.
This also holds for the other formats.

 pvesm export local:103/vm-103-disk-0.qcow2 qcow2+size target --with-snapshots 1

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See Also
--------

* link:/wiki/Storage:_Directory[Storage: Directory]

* link:/wiki/Storage:_GlusterFS[Storage: GlusterFS]

* link:/wiki/Storage:_User_Mode_iSCSI[Storage: User Mode iSCSI]

* link:/wiki/Storage:_iSCSI[Storage: iSCSI]

* link:/wiki/Storage:_LVM[Storage: LVM]

* link:/wiki/Storage:_LVM_Thin[Storage: LVM Thin]

* link:/wiki/Storage:_NFS[Storage: NFS]

* link:/wiki/Storage:_CIFS[Storage: CIFS]

* link:/wiki/Storage:_Proxmox_Backup_Server[Storage: Proxmox Backup Server]

* link:/wiki/Storage:_RBD[Storage: RBD]

* link:/wiki/Storage:_CephFS[Storage: CephFS]

* link:/wiki/Storage:_ZFS[Storage: ZFS]

* link:/wiki/Storage:_ZFS_over_ISCSI[Storage: ZFS over ISCSI]

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// backend documentation

include::pve-storage-dir.adoc[]

include::pve-storage-nfs.adoc[]

include::pve-storage-cifs.adoc[]

include::pve-storage-pbs.adoc[]

include::pve-storage-glusterfs.adoc[]

include::pve-storage-zfspool.adoc[]

include::pve-storage-lvm.adoc[]

include::pve-storage-lvmthin.adoc[]

include::pve-storage-iscsi.adoc[]

include::pve-storage-iscsidirect.adoc[]

include::pve-storage-rbd.adoc[]

include::pve-storage-cephfs.adoc[]

include::pve-storage-btrfs.adoc[]

include::pve-storage-zfs.adoc[]


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