Raw storage models

A raw storage volume can be directly mapped to a physical or virtual machine from the host computer over the network from SAN infrastructure or a physical machine, provided a storage volume manager is present.

The virtualization platform uses protocols, such as iSCSI or Fiber Channel while trying to access such volumes over the network. Raw storage volume is modeled as an instance of the BMC_StorageVolume class.

Key attributes of BMC_StorageVolume for raw storage volume

The following table describes key attributes that identify raw storage volumes:

Attribute	Usage
Name	Identifies the storage volume allocated to a virtual machine. A unique device identifier that is returned from the storage system is populated in this attribute.
NameFormat	Specifies the heuristic method that is used to generate the Name value.
SystemName	Name of the computer system on which the storage volume is hosted.

Additional attributes of BMC_StorageVolume

The following table describes additional attributes of a raw storage volume:

Attribute	Description
LUNID	A logical unit number (LUN) is the identifier of a device, which is being addressed by the SCSI protocol or similar protocols, such as Fiber Channel and iSCSI.
BlockSize	Size of the blocks (in bytes) that form the given storage extent. If the block size is variable, make sure that you specify the maximum block size in bytes. If the block size is unknown, specify a value of 1.
NumberOfBlocks	Total number of logical contiguous blocks that form the given storage extent. You can calculate the total size of the storage extent by multiplying BlockSize by the value of the NumberOfBlocks attribute. If the BlockSize is 1, this property is the total size of the extent.
AvailableCapacity	Indicates the total amount of free space (in bytes) that is available on the given storage extent. If the free space is unknown, specify a value of 0.
ConnectionType	The storage protocol used to communicate with the storage controller, for example, SCSI, iSCSI, FCoE, and Infiniband.

Storage volumes allocated to a virtual machine

You can model storage volume allocations to virtual machines (VMs) by using the BMC_StorageVolume class and associating it with the host computer using the SYSTEMDEVICE relationship.

The following figure illustrates a simple scenario where a storage volume is used in a VM:

Storage volumes allocated to a virtual machine from a resource pool

You can model the storage resource pools of virtual machines (VMs) and storage systems as described in the preceding Storage volumes allocated to a virtual machine section.

You must model the raw device that is mapped directly to a VM by using the BMC_StorageVolume class. You associate this class to the resource pool by using the ELEMENTALLOCATEDFROM relationship and the BMC_ComputerSystem class that represents the virtual system by using the SYSTEMDEVICE relationship.

The following figure illustrates an example of allocating a storage volume to a VM from a storage system:

Relationships for storage systems

The following table describes the relationships used for storage systems. Use the value listed in the table to specify the name for a relationship between any two storage classes:

Relationship	Relationship class	Value of Name attribute
Storage subsystem and an operating system	BMC_Dependency	STORAGESUBSYSTEMOS
Storage subsystem and a DASD	BMC_HostedSystemComponents	STORAGESUBSYSTEMDASD
Storage subsystem and a tape drive	BMC_HostedSystemComponents	STORAGESUBSYSTEMTAPE
File system hosted on a physical or virtual machine	BMC_HostedSystemComponents	HOSTEDFILESYSTEM
A logical disk allocated to a virtual machine	BMC_HostedSystemComponents	SYSTEMDEVICE
A file system residing on a logical disk	BMC_Dependency	RESIDESON
A storage volume allocated to a virtual machine	BMC_HostedSystemComponents	SYSTEMDEVICE
Relationship between a remote mounted file system such as NFS and the file system where it actually resides.	BMC_Dependency	MOUNTEDON