Local Storage Datastore

This storage configuration uses the local storage area of each Host to run VMs. Additionally you’ll need a storage area for the VM disk image repository. Disk images are transferred from the repository to the Hosts using the SSH protocol.

Front-end Setup

The Front-end needs to prepare the storage area for:

• Image Datastores to store the image repository.
• System Datastores to hold temporary disks and files for VMs stopped and undeployed.

Simply make sure that there is enough space under /var/lib/one/datastores to store images and the disks of the stopped and undeployed Virtual Machines. Note that /var/lib/one/datastores can be mounted from any NAS/SAN server in your network.

Host Setup

Just make sure that there is enough space under /var/lib/one/datastores to store the disks of running VMs on that Host.

OpenNebula Configuration

Once the Hosts and Front-end storage is set up, configuring OpenNebula comprises the creation of an Image and System Datastores.

Create System Datastore

To create a new System Datastore, you need to set the following (template) parameters:

You can do this either in Sunstone or through the CLI; for example, to create a local System Datastore simply enter:

$ cat systemds.txt
NAME    = local_system
TM_MAD  = local
TYPE    = SYSTEM_DS

$ onedatastore create systemds.txt
ID: 101

Create Image Datastore

To create a new Image Datastore, you need to set the following (template) parameters:

For example, the following illustrates the creation of a Local Datastore:

$ cat ds.conf
NAME   = local_images
DS_MAD = fs
TM_MAD = local

$ onedatastore create ds.conf
ID: 100

Also note that there are additional attributes that can be set. Check the datastore template attributes.

Additional Configuration

• DD_BLOCK_SIZE: Block size for dd operations (default: 64kB). Can be set in /var/lib/one/remotes/etc/datastore/fs/fs.conf.
• SUPPORTED_FS: Comma-separated list of every filesystem supported for creating formatted datablocks. Can be set in /var/lib/one/remotes/etc/datastore/datastore.conf.
• FS_OPTS_<FS>: Options for creating the filesystem for formatted datablocks. Can be set in /var/lib/one/remotes/etc/datastore/datastore.conf for each filesystem type.
• SPARSE: If set to NO the images and disks in the image and system Datastore, respectively, will not be sparsed (i.e. the files will use all assigned space on the Datastore filesystem).

Datastore Drivers

There are currently two Local transfer drivers:

• local: reference Local driver since OpenNebula 6.10.2, used by default for newly-created datastores. Supports operations such as thin provisioning for images in qcow2 format.
• ssh: legacy but still supported for compatibility reasons. Unable to leverage advanced qcow2 features.

Datastore Internals

Images are saved into the corresponding datastore directory (/var/lib/one/datastores/<DATASTORE ID>). Also, for each running Virtual Machine there is a directory (named after the VM ID) in the corresponding System Datastore. These directories contain the VM disks and additional files, e.g., checkpoint or snapshots.

For example, a system with an Image Datastore (1) with three images and three Virtual Machines (VMs 0 and 2 running, and VM 7 stopped) running from System Datastore 0 would present the following layout:

/var/lib/one/datastores
|-- 0/
|   |-- 0/
|   |   |-- disk.0
|   |   `-- disk.1
|   |-- 2/
|   |   `-- disk.0
|   `-- 7/
|       |-- checkpoint
|       `-- disk.0
`-- 1
    |-- 05a38ae85311b9dbb4eb15a2010f11ce
    |-- 2bbec245b382fd833be35b0b0683ed09
    `-- d0e0df1fb8cfa88311ea54dfbcfc4b0c

In this case, the System Datastore is distributed among the Hosts. The local transfer driver uses the Hosts’ local storage to place the images of running Virtual Machines. All of the operations are then performed locally, but images still need to be copied to the Hosts, which can be a very resource-demanding operation.

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