110 IBM BladeCenter PS703 and PS704 Technical Overview and IntroductionFor a more detailed discussion about virtual networking, see the following web page:http://www.ibm.com/servers/aix/whitepapers/aix_vn.pdfVirtual SCSIVirtual SCSI is provided by the POWER Hypervisor and provides a virtualized implementationof the SCSI protocol. This implementation provides secure communication between the Clientpartition (AIX, Linux, or IBM i) and the VIOS in a client/sever relationship. The VIOS logicalpartition or virtual server owns the physical resources and acts as server for them or, in SCSIterms, target devices. The client logical partitions access the virtual SCSI backing storagedevices provided by the VIOS as clients.The virtual I/O adapters (virtual SCSI server adapter and a virtual SCSI client adapter) areconfigured using an SDMC or through IVM on POWER-based blade servers. The virtualSCSI server (target) adapter is responsible for executing any SCSI commands it receives. Itis owned by the VIOS partition. The virtual SCSI client adapter allows a client partition toaccess physical SCSI and SAN-attached devices and LUNs that are assigned to the clientpartition. The provisioning of virtual disk resources is provided by the VIOS.Physical disks presented to the VIOS can be assigned to a client partition in a number ofways: The entire disk is presented to the client partition. The disk is divided into several logical volumes, which can be presented to a single clientor multiple clients as virtual disks. Files can be created on these disks and file-backed storage devices can be created.The logical volumes or files can be assigned to separate partitions. Therefore, virtual SCSIenables sharing of adapters as well as disk devices.Figure 3-12 on page 111 shows an example where one physical disk is divided into twological volumes by the VIOS. Each of the two client partitions is assigned one logical volume,which is then accessed through a virtual I/O adapter (VSCSI Client Adapter). Inside the clientpartition, the disk is seen as a normal hdisk.Note: An SEA does not need to have an IP address configured to perform the Ethernetbridging functionality. Configuring an IP address is required to access the IVM.
