-include::attributes.txt[]
[[chapter-storage]]
ifdef::manvolnum[]
PVE({manvolnum})
================
+include::attributes.txt[]
NAME
----
ifndef::manvolnum[]
{pve} Storage
=============
+include::attributes.txt[]
endif::manvolnum[]
The {pve} storage model is very flexible. Virtual machine images
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
+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 future.
|NFS |nfs |file |yes |no |yes
|GlusterFS |glusterfs |file |yes |no |yes
|LVM |lvm |block |no |no |yes
-|LVM-thin |lvmthin |block |no |yes |beta
+|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
|=========================================================
TIP: It is possible to use LVM on top of an iSCSI storage. That way
-you get a 'shared' LVM storage.
+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 filesystem 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 filesystems.
+
+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 receives IO error. 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
+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 make perfect sense for shared storage,
-because the same 'shared' storage is accessible from all nodes. But is
+because the same ``shared'' storage is accessible from all nodes. But 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.
...
----
-NOTE: There is one special local storage pool named `local`. It refers to
-directory '/var/lib/vz' and is automatically generated at installation
-time.
-
The `<type>: <STORAGE_ID>` line starts the pool definition, which is then
-followed by a list of properties. Most properties have values, but some of them comes
-with reasonable default. In that case you can omit the value.
+followed by a list of properties. Most properties have values, but some of
+them come with reasonable default. In that 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
+.Default storage configuration (`/etc/pve/storage.cfg`)
+----
+dir: local
path /var/lib/vz
- content backup,iso,vztmpl,images,rootdir
- maxfiles 3
-====
+ 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
+----
Common Storage Properties
~~~~~~~~~~~~~~~~~~~~~~~~~
-A few storage properties are common among differenty storage types.
+A few storage properties are common among different storage types.
nodes::
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 supports all content types. One can set
+directories. Not all storage types support all content types. One can set
this property to select for what this storage is used for.
images:::
rootdir:::
-Allow to store Container data.
+Allow to store container data.
vztmpl:::
backup:::
-Backup files ('vzdump').
+Backup files (`vzdump`).
iso:::
WARNING: It is not advisable to use the same storage pool on different
-{pve} clusters. Some storage operation needs exclusive access to the
+{pve} clusters. Some storage operation need exclusive access to the
storage, so proper locking is required. While this is implemented
-within an cluster, it does not work between different clusters.
+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 volume identifier. A volume
+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:
Volume Ownership
~~~~~~~~~~~~~~~~
-There exists an ownership relation for 'image' type volumes. Each such
+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 remove all
+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
--------------------------------
-I think it is required to understand the concept behind storage pools
-and volume identifier, but in real life, you are not forced to do any
+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
+Nevertheless, there is a command line tool called `pvesm` (``{pve}
+Storage Manager''), which is able to perform common storage management
tasks.
pvesm path <VOLUME_ID>
+ifdef::wiki[]
+
+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:_RBD[Storage: RBD]
+
+* link:/wiki/Storage:_ZFS[Storage: ZFS]
+
+
+endif::wiki[]
+
+ifndef::wiki[]
+
// backend documentation
include::pve-storage-dir.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[]
+
ifdef::manvolnum[]
include::pve-copyright.adoc[]
endif::manvolnum[]
+endif::wiki[]
+
projects / pve-docs.git / blobdiff