Two fundamental parts of the Oracle VM infrastructure, storage and networking, are not provided as part of the product itself, but are required in order for the product to function properly. Since the type of storage that a deployment may use can vary dependent on the deployment's requirements, Oracle VM provides support for a range of different storage types and includes mechanisms to enable different support types within the environment. Equally, network design and configuration can vary depending on requirements, hardware and cabling. Oracle VM caters to a range of complex network configurations and provides tools to configure systems within the environment to connect to each other according to a specific network design.
Oracle VM can use any of the following types of storage:
Local disks.
Shared Network Attached Storage - NFS.
Shared iSCSI SANs: abstracted LUNs or raw disks accessible over existing network infrastructure.
Shared Fibre Channel SANs connected to one or more host bus adapters (HBAs).
OCFS2 (Oracle Cluster File System) is used in the storage configurations that are not based on NFS.
To configure access to different storage types across Oracle VM Servers within a deployment, Oracle VM makes use of Oracle Storage Connect plug-ins. Storage Connect plug-ins are packaged and distributed as RPM packages and deployed on the Oracle VM Servers. They are divided in two major categories: storage array plug-ins for any block based storage, and file system plug-ins for any network file system based storage. Generic plugins are provided by Oracle for each of these storage types, however storage vendors may provide specialized plugins that expose further features to Oracle VM via the Oracle Storage Connect framework.
The main benefits of the plug-in approach are:
Flexibility: Use and integrate with your existing storage infrastructure, choose between file-based and block-based solutions, and use local storage for testing purposes or virtual machines of minor importance. Use generic or vendor-specific plug-ins depending on your available hardware or any new hardware you select.
Scalability: Add more storage providers of your preferred type and present them to your server pools as your need for storage increases. Reduce the amount of storage again if the higher storage requirements are temporary. Provision your storage with redundancy and multipathing according to your requirements and preferences.
Extensibility: If you upgrade your storage, consider the added functionality of vendor-specific plug-ins. If you select hardware for which Oracle Storage Connect plug-ins are available, ask the manufacturer for the RPM and install the plug-in on the Oracle VM Servers with access to this storage hardware.
Oracle VM always requires a location to store environment resources that are essential to the creation and management of virtual machines. These resources include virtual appliances and VM templates, ISO files (virtual DVD images), VM configuration files and VM virtual disks. The location of such a group of resources is called a storage repository. You present a storage repository to the Oracle VM Servers that need access to those resources; typically all servers in a server pool.
Storage repositories can be configured on an NFS file system or on a physical disk (LUN) of a storage array. However, for storage repositories on physical disk, the servers with access to it must be members of a clustered server pool. In general, the use of shared storage is recommended for the purpose of hosting a storage repository, however Oracle VM is capable of performing live migration of a virtual machine running from a repository hosted on local storage, by taking advantage of features within OCFS2. For unclustered server pools only file server storage is available. For details about the use of storage repositories, see Section 3.9, “Where are Virtual Machine Resources Located?”.
Clustering adds another storage element to the environment: the server pool file system. During server pool creation, the server pool file system specified for the new server pool is accessed and formatted as an OCFS2 file system, whether the file system is accessed by the Oracle VM Servers as an NFS share, a FC LUN or iSCSI LUN. This formatting creates several management areas on the file system including a region for the global disk heartbeat. The server pool file system plays a key role in clustering and therefore in the high-availability configuration of the Oracle VM environment. Note that where a clustered server pool is created, shared storage is required to host the server pool file system. For details about server pool clustering, see Section 6.9, “How do Server Pool Clusters Work?”.
The storage element that is most tangible and visible to all users of Oracle VM is the virtual machine disk. A VM disk is either a disk image file in a storage repository or a raw physical disk. If a physical disk (LUN) is used, it is attached directly to the VM in the same way it would be to a physical machine. For details about virtual machine operation, see Chapter 7, Understanding Virtual Machines. Again, the availability of VM disks in a storage location with shared access from all Oracle VM Servers in the server pool is preferred for VM high-availability.
Storage is described in more detail in Chapter 3, Understanding Storage.
The networking infrastructure in the Oracle VM environment comprises connections between:
Oracle VM Servers within the environment.
Oracle VM Manager and all Oracle VM Servers in the environment.
Oracle VM Server and the storage subsystems that it uses.
Virtual machines running in a server pool.
Virtual machines and external private or public networks.
These networking connections can leverage features supported by Oracle VM, such as networked file systems, clustering, redundancy and load balancing, bridging, and support for Virtual LANs (VLANs).
In Oracle VM Manager, network configuration is the mapping of available network interfaces on the Oracle VM Servers to a set of logical Ethernet networks. The physical network is the collection of physical connections in Oracle VM Manager and all Oracle VM Servers, and the switches and routers that allow information to reach its destination. A logical network in Oracle VM is built on top of these physical connections. Before you define the logical networks in Oracle VM Manager, you have to review the physical network configuration that you intend to use, such as VLAN and subnet usage. You also take into account the number of network interfaces available to your Oracle VM Servers. The minimum recommended number of ports required on a single Oracle VM Server is two, although one would suffice for test or demonstration purposes. If you have more than two ports on your Oracle VM Servers, you can design more redundancy or traffic isolation in your environment.
Oracle VM identifies different network functions: server management, live migration, cluster heartbeat, virtual machine, and storage. All network functions can either be on dedicated or shared physical networks (except for a server local network used for virtual machines only). For example, a physical network can be dedicated to Virtual Machine or Storage only, or can be dedicated for all network functions. For details about network functions, see Section 5.6, “How are Network Functions Separated in Oracle VM?”.
After reviewing your physical network environment and deciding on the logical distribution and grouping of these physical objects, you create the logical constructs in Oracle VM Manager to implement your network design. These logical constructs include network bonds, VLAN Interfaces, networks and bridges. If your network design includes interface bonding, or aggregations of two ports, you create these network bonds first. These bonds are often used in conjunction with VLANs, when traffic from several VLANs is allowed to use the same bond. If your network environment comprises VLANs, your next step is to create VLAN Interfaces, determining which port or bond on each Oracle VM Server will accept traffic from which VLANs.
After careful evaluation of the available network building blocks and required network functions, you create the necessary logical networks by choosing one of these types:
Network with bonds and ports.
Network with VLANs only.
Hybrid network connecting bonds and ports, as well as VLAN interfaces.
Logical network on a single server (local server network).
For more detailed information about networking within Oracle VM, see Chapter 5, Understanding Networks.