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[[Category:Reference Documentation]]
[[Category:Reference Documentation]]
<pvehide>
The Proxmox VE 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.
Table 1. Available storage types
Description
Plugin type
Level
Shared
Snapshots
Stable
ZFS (local)
zfspool
both1
no
yes
yes
Directory
dir
file
no
no2
yes
BTRFS
btrfs
file
no
yes
technology preview
NFS
nfs
file
yes
no2
yes
CIFS
cifs
file
yes
no2
yes
Proxmox Backup
pbs
both
yes
n/a
yes
GlusterFS
glusterfs
file
yes
no2
yes
CephFS
cephfs
file
yes
yes
yes
LVM
lvm
block
no3
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 &#8220;Snapshots&#8221; feature also support thin
provisioning.
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 Proxmox VE 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 &#8220;shared&#8221; 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 &lt;type&gt;, and is uniquely identified by its
&lt;STORAGE_ID&gt;. A pool configuration looks like this:
&lt;type&gt;: &lt;STORAGE_ID&gt;
        &lt;property&gt; &lt;value&gt;
        &lt;property&gt; &lt;value&gt;
        &lt;property&gt;
        ...
The &lt;type&gt;: &lt;STORAGE_ID&gt; 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 Proxmox VE 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
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. Proxmox VE 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
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.
It is not advisable to use the same storage pool on different
Proxmox VE 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 &lt;STORAGE_ID&gt;, followed by a storage type
dependent volume name, separated by colon. A valid &lt;VOLUME_ID&gt; 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 &lt;VOLUME_ID&gt; use:
pvesm path &lt;VOLUME_ID&gt;
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 (&#8220;Proxmox VE
Storage Manager&#8221;), which is able to perform common storage management
tasks.
Examples
Add storage pools
pvesm add &lt;TYPE&gt; &lt;STORAGE_ID&gt; &lt;OPTIONS&gt;
pvesm add dir &lt;STORAGE_ID&gt; --path &lt;PATH&gt;
pvesm add nfs &lt;STORAGE_ID&gt; --path &lt;PATH&gt; --server &lt;SERVER&gt; --export &lt;EXPORT&gt;
pvesm add lvm &lt;STORAGE_ID&gt; --vgname &lt;VGNAME&gt;
pvesm add iscsi &lt;STORAGE_ID&gt; --portal &lt;HOST[:PORT]&gt; --target &lt;TARGET&gt;
Disable storage pools
pvesm set &lt;STORAGE_ID&gt; --disable 1
Enable storage pools
pvesm set &lt;STORAGE_ID&gt; --disable 0
Change/set storage options
pvesm set &lt;STORAGE_ID&gt; &lt;OPTIONS&gt;
pvesm set &lt;STORAGE_ID&gt; --shared 1
pvesm set local --format qcow2
pvesm set &lt;STORAGE_ID&gt; --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 &lt;STORAGE_ID&gt;
Allocate volumes
pvesm alloc &lt;STORAGE_ID&gt; &lt;VMID&gt; &lt;name&gt; &lt;size&gt; [--format &lt;raw|qcow2&gt;]
Allocate a 4G volume in local storage. The name is auto-generated if
you pass an empty string as &lt;name&gt;
pvesm alloc local &lt;VMID&gt; '' 4G
Free volumes
pvesm free &lt;VOLUME_ID&gt;
This really destroys all volume data.
List storage status
pvesm status
List storage contents
pvesm list &lt;STORAGE_ID&gt; [--vmid &lt;VMID&gt;]
List volumes allocated by VMID
pvesm list &lt;STORAGE_ID&gt; --vmid &lt;VMID&gt;
List iso images
pvesm list &lt;STORAGE_ID&gt; --content iso
List container templates
pvesm list &lt;STORAGE_ID&gt; --content vztmpl
Show file system path for a volume
pvesm path &lt;VOLUME_ID&gt;
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
See Also
Storage: Directory
Storage: GlusterFS
Storage: User Mode iSCSI
Storage: iSCSI
Storage: LVM
Storage: LVM Thin
Storage: NFS
Storage: CIFS
Storage: Proxmox Backup Server
Storage: RBD
Storage: CephFS
Storage: ZFS
Storage: ZFS over ISCSI
</pvehide>
<!--PVE_IMPORT_END_MARKER-->

Latest revision as of 17:30, 6 March 2024

The Proxmox VE 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.

Table 1. Available storage types
Description Plugin type Level Shared Snapshots Stable

ZFS (local)

zfspool

both1

no

yes

yes

Directory

dir

file

no

no2

yes

BTRFS

btrfs

file

no

yes

technology preview

NFS

nfs

file

yes

no2

yes

CIFS

cifs

file

yes

no2

yes

Proxmox Backup

pbs

both

yes

n/a

yes

GlusterFS

glusterfs

file

yes

no2

yes

CephFS

cephfs

file

yes

yes

yes

LVM

lvm

block

no3

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 Proxmox VE 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 Proxmox VE 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. Proxmox VE 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 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 Proxmox VE 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 (“Proxmox VE 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