Virtual I/O Server storage subsystem overview

Learn about the Virtual I/O Server storage subsystem.

The Virtual I/O Server storage subsystem is a standard storage subsystem that provides standard logical unit numbers (LUNs) compliant with the Small Computer Serial Interface (SCSI). The Virtual I/O Server is a localized storage subsystem. Unlike typical storage subsystems that are physically located in the SAN, the SCSI devices exported by the Virtual I/O Server are limited to the domain within the server.

Like typical disk storage subsystems, the Virtual I/O Server has a distinct front end and back end. The front end is the interface to which client logical partitions attach to view standard SCSI-compliant LUNs. Devices on the front end are called virtual SCSI devices. The back end is made up of physical storage resources. These physical resources include physical disk storage, both SAN devices and internal storage devices, optical devices, tape devices, logical volumes, and files.

To create a virtual device, some physical storage must be allocated and assigned to a virtual SCSI server adapter. This process creates a virtual device instance (vtscsiX or vtoptX). The device instance can be considered a mapping device. It is not a real device, but rather a mechanism for managing the mapping of the portion of physical back-end storage to the front-end virtual SCSI device. This mapping device re-creates the physical-to-virtual allocations in a persistent manner when the Virtual I/O Server is restarted.