Storage pool type: `dir`

Proxmox VE can use local directories or locally mounted shares for storage. A directory is a file level storage, so you can store any content type like virtual disk images, containers, templates, ISO images or backup files.

| You can mount additional storages via standard linux `/etc/fstab`, and then define a directory storage for that mount point. This way you can use any file system supported by Linux.

This backend assumes that the underlying directory is POSIX compatible, but nothing else. This implies that you cannot create snapshots at the storage level. But there exists a workaround for VM images using the `qcow2` file format, because that format supports snapshots internally.

| Some storage types do not support `O_DIRECT`, so you can’t use cache mode `none` with such storages. Simply use cache mode `writeback` instead.

We use a predefined directory layout to store different content types into different sub-directories. This layout is used by all file level storage backends.

Table 1. Directory layout
Content type | Subdir
--- | ---
VM images | ``images/<VMID>/``
ISO images | ``template/iso/``
Container templates | ``template/cache/``
Backup files | ``dump/``
Snippets | ``snippets/``

## Configuration

This backend supports all common storage properties, and adds two additional properties. The `path` property is used to specify the directory. This needs to be an absolute file system path.

The optional `content-dirs` property allows for the default layout to be changed. It consists of a comma-separated list of identifiers in the following format:

    vtype=path

Where `vtype` is one of the allowed content types for the storage, and `path` is a path relative to the mountpoint of the storage.

Configuration Example (`/etc/pve/storage.cfg`)

    dir: backup
            path /mnt/backup
            content backup
            prune-backups keep-last=7
            max-protected-backups 3
            content-dirs backup=custom/backup/dir

The above configuration defines a storage pool called `backup`. That pool can be used to store up to 7 regular backups (`keep-last=7`) and 3 protected backups per VM. The real path for the backup files is `/mnt/backup/custom/backup/dir/...`.

## File naming conventions

This backend uses a well defined naming scheme for VM images:

    vm-<VMID>-<NAME>.<FORMAT>

`<VMID>`

  This specifies the owner VM.

`<NAME>`

  This can be an arbitrary name (`ascii`) without white space. The backend uses `disk-[N]` as default, where `[N]` is replaced by an integer to make the name unique.

`<FORMAT>`

  Specifies the image format (`raw|qcow2|vmdk`).

When you create a VM template, all VM images are renamed to indicate that they are now read-only, and can be used as a base image for clones:

    base-<VMID>-<NAME>.<FORMAT>

| Such base images are used to generate cloned images. So it is important that those files are read-only, and never get modified. The backend changes the access mode to `0444`, and sets the immutable flag (`chattr +i`) if the storage supports that.

## Storage Features

As mentioned above, most file systems do not support snapshots out of the box. To workaround that problem, this backend is able to use `qcow2` internal snapshot capabilities.

Same applies to clones. The backend uses the `qcow2` base image feature to create clones.

Table 2. Storage features for backend `dir`
Content types | Image formats | Shared | Snapshots | Clones
--- | --- | --- | --- | ---
`images rootdir vztmpl iso backup snippets` | `raw qcow2 vmdk subvol` | no | qcow2 | qcow2

## Examples

Please use the following command to allocate a 4GB image on storage `local`:

    # pvesm alloc local 100 vm-100-disk10.raw 4G
    Formatting '/var/lib/vz/images/100/vm-100-disk10.raw', fmt=raw size=4294967296
    successfully created 'local:100/vm-100-disk10.raw'

| The image name must conform to above naming conventions.

The real file system path is shown with:

    # pvesm path local:100/vm-100-disk10.raw
    /var/lib/vz/images/100/vm-100-disk10.raw

And you can remove the image with:

    # pvesm free local:100/vm-100-disk10.raw

## See Also

- Storage