Definition

Multipath I/O (MPIO)

Part of the Storage-area network (SAN) glossary:

Multipath I/O (MPIO) is a Microsoft framework designed to mitigate the effects of a host bus adapter (HBA) failure by providing an alternate data path between storage devices and a Windows operating system. MPIO enables up to 32 alternate paths to add redundancy and load balancing for Windows storage environments. 

Pathing is a networking approach used to address the specific needs of storage networks by changing the way that communication paths are managed and organized. Unlike connection failures in message networks -- which generally just require that the connection be retried -- in storage networks, a failure is more likely to cause a system crash. Storage networks also require faster error recovery. 

Technically, MPIO represents a hybrid approach to multipathing, combining software specific to each HBA -- the Device Specific Module (DSM) -- with the MPIO features integrated into the Windows operating system. While the DSMs must be written for specific hardware and cannot be generic, Microsoft designed MPIO to be as HBA-agnostic as possible. As such, it depends on the rest of the hardware and software to work correctly in order to do its job.

MPIO requires at least two HBAs connected to the storage device. (A dual-port HBA may provide two data paths, but it still represents a single point of failure.) In a storage area network (SAN) you also need to ensure that any switches or routers laying in the data path have enough path management intelligence to handle disruptions caused by an HBA failure.

This was last updated in July 2012
Contributor(s): Rick Cook, Ivy Wigmore
Posted by: Margaret Rouse

Related Terms

Definitions

Glossaries

  • Storage-area network (SAN)

    - Terms related to storage area networks, including definitions about SAN management and words and phrases about virtual SANs, Fibre Channel and iSCSI SANs.

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question About Multipath I/O (MPIO)Powered by ITKnowledgeExchange.com

Get answers from your peers on your most technical challenges

Tech TalkComment

Share
Comments

    Results

    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.