DISCUSIÓN

You can configure a compute host to provide local storage for use by VMs.

Local storage can be used to provide improved disk access performance for VMs instantiated on the host. Caution:

Local storage is ephemeral.

• Unlike Cinder-based storage, local storage does not persist if the instance is terminated or the compute node fails.

• Live migration is not currently supported for an instance using local storage. Locking the host initiates a cold migration. The local storage for the instance is rebuilt.

• Resizing of local storage is partly supported. If the reconfigured instance is instantiated on the same host, then any root or ephemeral disks that use local storage are resized with their data preserved. Swap

disks that use local storage are rebuilt. If the instance is migrated to another host, only cold migration is supported. All local storage for the instance is rebuilt.

To provide local storage on a compute host, add a local volume group called nova-local to the host. This

automatically includes the host in the local_storage_hosts host aggregate. The Nova scheduler draws from this host aggregate to instantiate VMs that require local storage.

To populate the nova-local group with storage resources, you must also add physical volumes created on local disks. You must manually allocate space on the local volume group for an instances logical volume. For more information, see Instances Logical Volume Considerations on page 69.

Caution:

If less than the minimum required space is available for the instances logical volume, the compute host cannot be unlocked.

As an alternative to the web administration interface, you can use the CLI to configure the host for local storage. For more information, see Managing Local Volume Groups on page 128 and Managing Physical Volumes on page 129.

1. Lock the host to make changes.

a) On the Admin menu of the web administration interface, open the System Panel section, and then select Inventory.

b) Select the Hosts tab.

c) Open the More drop-down list for the host, and then select Lock Host. d) Wait for the host to be reported as Locked.

2. Open the Inventory Detail page for the locked host. In the Host Name column, click the name of the host. 3. Select the Storage tab.

For a compute node, the storage tab displays three lists: Disks

Physical disks installed in the compute node. Local Volume Groups

Groups of physical volumes available for VM storage. Physical Volumes

Partitions that have been initialized for logical volume management (LVM) and assigned to a local volume group.

4. If required, add the nova-local group to the Local Volume Groups list.

The Local Volume Groups list displays groups of physical volumes designated for use as local storage. The default group for use by VMs is called nova-local. If this group is not listed, you can create it by clicking Add Local Volume Group, and then accepting the defaults in the dialog box that appears.

The nova-local group is shown in the list.

5. Add a physical volume to the nova-local group.

The Physical Volumes list displays LVM volumes that have been created and added to a Local Volume Group. To add a new one, click Add Physical Volume and complete the dialog box that appears.

Note:

The Local Volume Group drop-down selection is automatically set to nova-local, and cannot be changed.

Use the Disks drop-down menu to select a disk to provide storage. For the root disk, a designated partition (local_pv) is used.

You can add any number of physical volumes to the nova-local group, limited only by the number of available disks.

A physical volume is created and added to the nova-local group.

6. Allocate space for the instances logical volume.

Select the Parameters tab.

If the total space in the volume group is less than 80GB (81920 MiB), then you must allocate at least 2048 MiB. If the volume group is greater than 80GB (81920 MiB), then you must allocate at least 5120 MiB. The actual size is limited to ensure at least 50% free space in the volume group for creating disks for launched instances. For more information, see Instances Logical Volume Considerations on page 69

7. Unlock the host to make the changes take effect.

The compute host is ready to provide local storage for use by VMs. Because a nova-local local volume group has been added, the host is automatically included in the local_storage_hosts host aggregate.

To return a host to the remote_storage_hosts host aggregate, so that it is used to instantiate VMs configured for remote Cinder-based storage, delete the nova-local local volume group.

Caution:

VMs instantiated on the compute node must be migrated or terminated before the host is reconfigured for remote storage.

To configure a VM to use local storage or remote Cinder-based storage, or to be instantiated on any compute host regardless of storage type, see Specifying Local Storage for VM Ephemeral Resources on page 153.

To add disks to a compute node for extra local storage, see Adjusting Resources on a Compute Node on page 115