I2O Cuts RAID Costs

Posted on October 01, 1997

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I2O Cuts RAID Costs

The I2O spec promises to cut PCI-RAID costs for OEMs and end-users, while reducing storage integration hassles.

Laura Cratin

Symbios Logic

As I2O architectures break into the PCI-RAID market over the next year, RAID vendors, OEMs, and end-users will realize significant cost benefits. To date, a PCI-RAID vendor has been required to deliver the complete RAID solution, including operating system-specific software and I/O drivers. With I2O PCI-RAID, OEMs will be able to complete the RAID picture with I2O software modules from individual vendors, allowing I2O RAID vendors to focus solely on providing the best RAID components, not OS- and I/O-specific pieces.

In addition, I2O will allow RAID vendors to use fewer developers and test personnel. The result: quicker time-to-market. The lower R&D cost of developing I2O-based RAID will allow more companies to enter the market, which will foster competition and ultimately translate into lower prices for OEMs and end-users.

The I2O (intelligent input/output) architecture is an industry standard for distributing I/O functions across multiple processors. The key advantage is greater I/O design flexibility and increased bandwidth performance with less CPU use. The I2O architecture has three primary modules: OS service modules (OSMs), which are host-specific; hardware device modules (HDMs), which are I/O-specific; and intermediate service modules (ISMs), which add functionality, such as RAID.

I2O defines a standard message-passing scheme to achieve clean separation and I/O abstraction between these modules. Each software module has a unique function:

OSM is a software module that contains the OS-specific code. An OSM is needed for each operating system and upper-level protocol. The OSM has no knowledge of the underlying hardware protocol. Once an OSM is created, however, it can be used with any number of different HDMs.

HDM is a software module that contains all of the hardware-specific code. An HDM is required for each unique I/O device, such as SCSI and Fibre Channel.

ISM provides additional functionality, such as RAID. ISMs are not OS-specific or hardware protocol-specific. ISMs are targeted at supporting specific applications or providing key value (such as backup) for customers or specific environments.

I2O Advantages

The I2O standard architecture has paved the way for PCI-RAID product development, bringing together the advantages of faster, easier development and low-cost integration and testing. With the integration of I2O and PCI-RAID, OEMs will be able to obtain individual I2O modules for their PCI-RAID solutions at a lower cost. OEMs will automatically get OSMs from their OS suppliers as a part of the OS; they will be able to choose optimal RAID ISMs from the best (and/or least expensive) RAID vendor; and they will be able to obtain I/O HDMs from a variety of I/O vendors. The I2O real-time operating system (IRTOS) will glue these pieces together. The numerous benefits resulting from "mix-and-match" PCI-RAID solutions will be seen by RAID vendors, OEMs, and end-users alike--and the savings will be passed along to end-users.

Current PCI-RAID solutions, which do not incorporate the I2O architecture, require OEMs to choose a single PCI-RAID supplier for end-to-end RAID solutions (see diagram B). RAID suppliers have to modify drivers and utilities for each new OS release, such as Windows NT, NetWare, and UnixWare, and low-level drivers for each new I/O protocol, such as SCSI or Fibre Channel.

In addition, RAID vendors have to implement a unique message-passing methodology that is unlike any other vendor`s, making the underlying RAID code proprietary to that vendor. The non-I2O RAID supplier passes these continuous development, integration, and testing costs to the OEM. Consequently, not only is an OEM forced to buy PCI-RAID system components from a single vendor at a higher cost, but the software and hardware components do not operate with the components of other vendors.

As more I2O PCI-RAID solutions become available, OEMs will be able to create tailored RAID products--and at a much lower cost. Since the various software modules will be sourced from OS, RAID, RTOS, and I/O vendors, OEMs will be able to choose the I2O PCI-RAID solution that is in step with their respective price/performance goals--and that is in line with end-users` budgets.

Currently, as many as half of PCI-RAID software programmers have been developing OS or hardware-specific software. With I2O PCI-RAID, RAID suppliers will only have to develop RAID ISM code, leaving the development of OSM and HDM to specialized vendors. Testing will also be simplified since module testing will focus only on the RAID ISM. Also, standard I2O software will make it easier to test I2O message handling. Lower development and testing costs will be realized by RAID vendors and then passed on to OEMs.

Faster Time to Market

Because each vendor, playing its unique part in developing the complete I2O solution, is working in parallel with other vendors and because each vendor`s resources are focused purely on its area of specialty, overall development, integration, and testing time is significantly lower. I/O HDMs are available from many hardware vendors. Members of the I2O Special Interest Group (SIG) can already access Windows NT, NetWare, and UnixWare block storage OSMs, which will be available on the I2O SIG web site (www. i2osig.org).

Since HDMs and OSMs are readily available, RAID ISM is the only missing piece of the I2O PCI-RAID puzzle. However, now that RAID vendors only need to develop and test one module, many are rushing to market with RAID ISMs.

When written to the I2O specification, OSMs, HDMs, and ISMs from the various vendors can be used interchangeably. No longer having to integrate each component with each new OS release, RAID vendors will be able to focus solely on improving performance and feature sets and on ensuring the robustness of the RAID code. PCI-RAID`s inherent interoperability and compatibility will allow for increased competition in the RAID market, creating a wider selection of vendors and products, which in turn will allow OEMs and end-users to choose the I2O RAID solutions that best meet their price/performance goals.

The I2O architectural standard will allow OEMs to provide PCI-RAID solutions at significantly reduced cost over existing non-I2O RAID solutions. With the standardization of I2O messaging, RAID software suppliers will be able to reduce software development, integration, and testing costs, passing these savings to OEMs and end-users. I2O RAID software vendors will not need to migrate code for each new OS release and they will not need to develop new code for each new I/O protocol. The ease of development and integration, as well as the vastly reduced cost of entry, will undoubtedly attract more players into the PCI-RAID arena, creating more competition and ultimately reducing the total cost of ownership of PCI-RAID systems.

For more information about the I2O Special Interest Group, call (415) 750-8352 or visit www.i2osig.org.

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Diagram A: I2O defines a standard message-passing scheme to separate various software modules.

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Diagram B: Non-I2O solutions require OEMs to choose a single RAID supplier for end-to-end RAID solutions.

Laura Cratin is the I2O software product manager for Symbios Logic Inc. in Fort Collins, CO.


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