Virtual Storage Technology (VST) — Overview

Virtual Storage Technology (VST) offers the most advanced form of high performance RAID in the market place today, with a highly portable software only solution that runs entirely on an Intel x86 compatible processor based system without the need for additional hardware . VST utilizes simple disk I/O ports either built into the motherboard or on a simple disk I/O adapter card instead of costly RAID-on-chip implementations. Capable of outperforming any standard hardware RAID adapter through it’s innovative multi-controller disk I/O port spanning algorithm (see fig 1), virtual technology combined with today’s multi-processor environment, has allowed a new class of storage technology to emerge.

The VST core technology consists of three main components:

Core VST Engine

The core VST engine services disk I/O access requests from the host computer via the VST host interface layer, and converts them into multiple block level disk I/O requests based on the type of RAID array that has been formed in a prior setup or installation procedure. The core engine acts like any other RAID engine i.e. creates redundancy information and determining when a disk drive has failed, then applying the appropriate recovery algorithms as appropriate. In that respect the VST engine is no different from any other RAID engine, with the only exception being that the redundancy calculations are made completely by the host x86 CPU using MMX or SSE instructions commonly available in Intel and AMD CPUs instead of relying on a dedicated redundancy or parity XOR engine present on an add-in card’s I/O controller or RAID-on-chip (ROC).

As the core VST engine runs at a layer higher than a conventional hardware RAID adapter, it is able to see and utilize a number of disk I/O ports from multiple controllers that may be present in the system. For example, many motherboards now ship with 4-6 built in SATA ports that often go unused, made possible by VST’s virtual port I/O layer.

VST Virtual Port I/O Layer

This is where the multiple controller types are supported and allows each of the individual disk drives, be them SATA or SAS, to be presented to the VST core engine using a consistent interface. When ever a new disk I/O controller is introduced to the market, only this layer need be changed to address the features provided by the new driver.

VST Host Interface

Today, the VST host interface conforms to the standard SCSI I/O driver model allowing to seamlessly connect to any standard operating system. Different operating systems, such as Windows Vista, Linux or OS X may be supported by adapting this layer for each individual operating system without impacting the core VST engine.

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