Storage: Directory: Difference between revisions

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images using the qcow2 file format, because that format supports
images using the qcow2 file format, because that format supports
snapshots internally.
snapshots internally.
Some storage types do not support O_DIRECT, so you can’t use
Some storage types do not support O_DIRECT, so you can’t use
cache mode none with such storages. Simply use cache mode
cache mode none with such storages. Simply use cache mode
writeback instead.
writeback instead.
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Subdir
Subdir
VM images
VM images
images/<VMID>/
images/&lt;VMID&gt;/
ISO images
ISO images
template/iso/
template/iso/
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File naming conventions
File naming conventions
This backend uses a well defined naming scheme for VM images:
This backend uses a well defined naming scheme for VM images:
vm-<VMID>-<NAME>.<FORMAT>
vm-&lt;VMID&gt;-&lt;NAME&gt;.&lt;FORMAT&gt;
<VMID>
&lt;VMID&gt;
This specifies the owner VM.
This specifies the owner VM.
<NAME>
&lt;NAME&gt;
This can be an arbitrary name (ascii) without white space. The
This can be an arbitrary name (ascii) without white space. The
backend uses disk-[N] as default, where [N] is replaced by an
backend uses disk-[N] as default, where [N] is replaced by an
integer to make the name unique.
integer to make the name unique.
<FORMAT>
&lt;FORMAT&gt;
Specifies the image format (raw|qcow2|vmdk).
Specifies the image format (raw|qcow2|vmdk).
When you create a VM template, all VM images are renamed to indicate
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:
that they are now read-only, and can be used as a base image for clones:
base-<VMID>-<NAME>.<FORMAT>
base-&lt;VMID&gt;-&lt;NAME&gt;.&lt;FORMAT&gt;
Such base images are used to generate cloned images. So it is
Such base images are used to generate cloned images. So it is
important that those files are read-only, and never get modified. The
important that those files are read-only, and never get modified. The

Revision as of 10:39, 22 October 2016

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.

Note 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.

Tip 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>
Note 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'
Note 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