Storage: LVM Thin

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Storage pool type: lvmthin

LVM normally allocates blocks when you create a volume. LVM thin pools instead allocates blocks when they are written. This behaviour is called thin-provisioning, because volumes can be much larger than physically available space.

You can use the normal LVM command line tools to manage and create LVM thin pools (see man lvmthin for details). Assuming you already have a LVM volume group called pve, the following commands create a new LVM thin pool (size 100G) called data:

lvcreate -L 100G -n data pve
lvconvert --type thin-pool pve/data

Configuration

The LVM thin backend supports the common storage properties content, nodes, disable, and the following LVM specific properties:

vgname

LVM volume group name. This must point to an existing volume group.

thinpool

The name of the LVM thin pool.

Configuration Example (/etc/pve/storage.cfg)
lvmthin: local-lvm
        thinpool data
        vgname pve
        content rootdir,images

File naming conventions

The backend use basically the same naming conventions as the ZFS pool backend.

vm-<VMID>-<NAME>      // normal VM images

Storage Features

LVM thin is a block storage, but fully supports snapshots and clones efficiently. New volumes are automatically initialized with zero.

It must be mentioned that LVM thin pools cannot be shared across multiple nodes, so you can only use them as local storage.

Table 1. Storage features for backend lvmthin
Content types Image formats Shared Snapshots Clones

images rootdir

raw

no

yes

yes

Examples

List available LVM thin pools on volume group pve:

# pvesm lvmthinscan pve

See Also