Chapter 4 Hardware and Software Configuration 115
About Multipathing Software
Multipathing software enables you to define and control redundantphysical paths
to I/O devices such as disk storage arrays and network interfaces. If the active path
to a device becomes unavailable, the software automatically switches to an alternate
path to maintain availability.This capability is known as automatic failover.
Automatic failover allows a qualifed service provider to remove and replacethe
faulty component without impacting normal system operations.
Totake advantage of multipathing capabilities, your server must be configured with
redundant hardware, such as redundantnetwork interfaces or disk drives.
For the Sun Fire 280R system, two differenttypes of multipathing software are
available:
■Solaris IP Network Multipathing –Provides multipathing and load-balancing
capabilities for IP network interfaces
■VERITASVolume Manager – Includes a feature called Dynamic
Multipathing (DMP) for disk storage arrays
The Solaris implementation of IP Network Multipathing provides the following
configurable features:
■Failure detection– The ability to detect when one of a configured group of
network adapters fails and to automatically switch (failover) the network access
to an alternate adapter in the group.
■Repair detection –The ability to detect when a network adapter that failed
previously has been repaired and to automatically switch network access back
(failback) to include the repaired adapter.
■Load spreading– The ability to spread network packets across multiple network
adapters to achieve higher throughput. Load spreading occurs only when the
network traffic is flowing to multiple destinations using multiple connections.
For instructions on how to configure and administer Solaris IP Network
Multipathing, consult the IP Network Multipathing Administration Guide provided
with your specific Solaris release.
VERITASVolume Manager software actively supports multiported disk arrays. It
automatically recognizes multiple I/O paths to a particular disk device within an
array.VERITAS DMP provides increased reliability by providing a path failover
mechanism. If one connection to a disk is lost, VERITASVolume Manager continues