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Browse Prior Art Database

Method for enhanced MPIO path selection

IP.com Disclosure Number: IPCOM000016728D
Original Publication Date: 2003-Jul-11
Included in the Prior Art Database: 2003-Jul-11
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Abstract

Enhanced method for MPIO device path selection based on the physical elements of the SAN.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

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Method for enhanced MPIO path selection

Disclosed is a method for enhanced IO path selection within a multiple path IO (MPIO) product within a storage area network (SAN). An MPIO product allows for the use of multiple connections between a host and a specific device. The disclosed method would provide for an enhanced selection method for an MPIO device that would to take into account the properties of each connection or path to a specific device in the SAN. Having multiple connections between a host and a device allows for recovery of failed connections by issuing requests down an alternate connection as well as increase throughput by issuing requests via multiple connection on different adapters. A SAN is a collection of host bus adapters (HBA) connected to switches and hubs which are in turn connected eventually to end point devices such as disk arrays.

The proposed idea is for the MPIO product to have a next path selection algorithm that first picks an HBA using a round robin algorithm then a connection from that HBA to the device using a second round robin algorithm. The idea is to send each successive IO request out a different HBA so that load is spread across the different HBAs while still utilizing each connection from the host to the device. The MPIO product could mark a connection down or unusable when say an IO request fails on a connection but continue to use the adapter. The MPIO product would mark all connections down or unusable from an adapter should the HBA itself fail. Once a connection to device is marked as down the MPIO product would stop using that connection to issu...