Chapter 10. Multipath IO

Contents

10.1. Supported Hardware
10.2. System Configuration
10.3. Software Configuration
10.4. Using the Devices

Abstract

Linux multipathing provides IO failover and path load sharing for multipathed block devices. The multipath IO support in SUSEŽ Linux Enterprise Server is based on the Device Mapper multipath module of the Linux kernel and the multipath-tools userspace package.

Device mapping multipath IO features automatic configuration of the subsystem for a large variety of setups. Active/passive or active/active (with round-robin load balancing) configurations of up to eight paths to each device are supported.

multipath-tools take care of automatic path discovery and grouping as well as automated path retesting, so that a previously failed path is automatically reinstated when it becomes healthy again. This minimizes the need for administrator attention in a production environment.

Device mapping multipath IO supports partitions (with limitations) and LVM2. Software RAID is also supported, but automatic discovery is not available. To use software RAID with mdadm, /etc/mdadm.conf must be set up correctly. See Section 10.4, “Using the Devices” for more information.

Currently, device mapping multipath IO is not available for the boot partition, because the boot loader cannot handle multipath IO. Therefore it is recommended to set up a separate boot partition when using multipath IO.

10.1. Supported Hardware

Multipath IO is available on all platforms supported by SUSE Linux Enterprise Server. The following storage subsystems are detected automatically:

  • 3Pardata VV

  • Compaq HSV110 / MSA1000

  • DDN SAN MultiDirector

  • DEC HSG80

  • EMC CLARiiON CX

  • FSC CentricStor

  • HP HSV110 / A6189A / Open-

  • Hitachi DF400 / DF500 / DF600

  • IBM 3542 / ProFibre 4000R / F20 / SVC / DS6000 / DS8000

  • NETAPP

  • SGI TP9100 / TP9300 / TP9400 / TP9500

  • STK OPENstorage DS280

  • SUN StorEdge 3510 / T4

Most other storage subsystems should work, but require manual configuration in /etc/multipath.conf.

Storage subsystems that require special commands on failover from one path to the other or require special nonstandard error handling might require more extensive support. Therefore the DM framework has hooks for hardware handlers and one such handler for the EMC CLARiiON CX family of arrays is already provided.