Multipath I/O (多路径)
在计算机存储技术里,多路径提供了容错和性能提高,在计算机系统里CPU有多条物理路径通道,块存储设备通过总线,控制器,交换设备以及桥接设备来连接。

简单举例同一台计算机里1块SCSI磁盘连接2个SCSI控制器或者磁盘连接到两个FC端口。如果其中1个控制器，端口或交换设备故障，那操作系统就会自动切换I/O路径到冗余的控制器为应用程序使用,但这样可能会增加延迟.

一些多路径软件可以利用冗余的路径提高性能,例如:

Dynamic load balancing 动态负载均衡
Traffic shaping 流量控制
Automatic path management 自动路径管理
Dynamic reconfiguration 动态设置

Multipath I/O software implementations 多路径软件工具

一些操作系统自带支持多路径功能,如下

SGI IRIX - using the LV, XLV and later XVM volume managers (1990s and onwards)
AIX - MPIO Driver, AIX 5L 5.2 (October 2002) and later
HP-UX 11.31 (2007)
Linux - Device-Mapper Multipath . Linux kernel 2.6.13 (August 2005)
OpenVMS V7.2 (1999) and later
Solaris Multiplexed I/O (MPxIO), Solaris 8 (February 2000) and later
Windows MPIO Driver, Windows Server 2003 and Windows Server 2008 (April 2003)
FreeBSD - GEOM_FOX module
Mac OS X Leopard and Mac OS X Leopard Server 10.5.2


Multipath software products: (软件产品)

AntemetA. Multipathing Software solution for AIX for HP EVA Disk Arrays
NEC PathManager
EMC PowerPath
FalconStor IPStor DynaPath
Fujitsu Siemens MultiPath for Linux and Windows OS
Fujitsu ETERNUS Multipath Driver (ETERNUSmpd) for Solaris, Windows, Linux and AIX.
Hitachi HiCommand Dynamic Link Manager (HDLM)
HP StorageWorks Secure Path
NCR UNIX MP-RAS EMPATH for EMC Disk Arrays
NCR UNIX MP-RAS RDAC for Engenio Disk Arrays
ONStor SDM multipath
IBM System Storage Multipath Subsystem Device Driver (SDD), formerly Data Path Optimizer
Accusys PathGuard
Infortrend EonPath
Sun Multipath failover driver for Windows and AIX
Sun StorEdge Traffic Manager Software, included in Sun Java StorEdge Software suite
Linux
multipath-tools, used to drive the Device Mapper multipathing driver, first released on September 2003
Fibreutils package for QLogic HBAs
RDAC package for LSI disk controllers
lpfcdriver package for Emulex HBAs
Veritas
Veritas Storage Foundation (VxSF)
Veritas Volume Manager (VxVM)
Pillar Data Systems
Axiom Path Manager for AIX, Windows, Linux, and Solaris
Areca Multipath failover driver for Windows