Chapter 4 Understanding Repositories

A storage repository is used to store virtual machine resources, so that these resources can be made available to Oracle VM Servers in a server pool, without having to copy the resources to each Oracle VM Server. The Oracle VM Servers in a server pool gain access to these virtual machine resources by having the storage repository presented to them. If your storage is file-based storage, you can present a storage repository to multiple server pools. Alternatively, if your storage is physical disk-based, you can only present the storage repository to a single server pool.

A storage repository is essentially logical disk space made available through a file system on top of physical storage hardware. If the storage repository is created on a file server, for example an NFS share, then a file system is already present; if the repository is created on a LUN, an OCFS2 file system is first created. To gain better insight into the storage infrastructure underlying the repositories, refer to Chapter 3, Understanding Storage, and pay special attention to the information in Section 3.10, “Are there Guidelines for Configuring Storage?”.

This chapter provides information on the structure of storage repositories, describes how to create and manage them, and describes how you manage virtual machine resources contained within them.

You use the Repositories tab in Oracle VM Manager to create and configure storage repositories, and to present one or more storage repositories to Oracle VM Servers in a server pool. During the creation and configuration of the storage repository the Oracle VM Agent on the Oracle VM Server acts as the worker component performing the instructions given through Oracle VM Manager. This chapter discusses the flow of the operations you perform after the discovery of your physical storage hardware, LUNs, file systems and so on, in order to make a storage repository available to the Oracle VM Servers in your server pool. When the storage repository is accessible, you can start adding storage resources and building virtual machines with those resources.

Depending on the configuration of Oracle VM Servers in your environment, some restrictions may apply to the creation of storage repositories due to the nature of the storage. Keep in mind the following guidelines when working with storage repositories:

  • When using server pools without clustering functionality, two storage options are available: file servers (NFS) and local physical disks in a local storage array. Remember that local storage comes with some restrictions and may not be desirable in some environments, as described in Section 3.2.1, “Local Storage”.

  • Local storage, or unused disks in your Oracle VM Servers, are discovered as LUNs in a local storage array. If you want to use a single-server setup with local storage, be sure to deactivate clustering in your server pool. This eliminates the need for a server pool file system, which cannot be on a local disk.

  • Only a server pool with multiple servers, active clustering and attached storage (NFS, iSCSI, fibre channel) can offer high availability, load balancing and similar advanced functionality.

Note

Storage repositories are presented to individual Oracle VM Servers, and not necessarily to all Oracle VM Servers within a server pool. This means that it is possible that a repository may not be available for use on a particular server. You should keep this in mind when you deploy a virtual machine on a specific Oracle VM Server. To see which Oracle VM Servers have access to a storage repository, select the repository in the navigation pane and verify the access status in the management pane with the Perspective set to Info.

Warning

Never manually copy Oracle VM resources such as virtual machine configuration files from one repository to another, as this can cause duplication of UUIDs within the Oracle VM environment and can cause Oracle VM to malfunction. Always use the tools provided by Oracle VM Manager or the Oracle VM Manager Command Line Interface to move resources. For instance, to move a virtual machine configuration from one storage repository to another use the Move Virtual Machine wizard described in Section 7.7, “How Can a Virtual Machine be Moved or Migrated?”.