Alternate Path Software - Fujitsu IRF-1S series User Manual

Chapter 2 - Topologies and Operating Modes

Alternate Path Software

This is a software tool that manages multiple paths between the host operating
system and LUNs. The software manages the multiple paths by detecting
duplicate disk objects that represent a single LUN. It then designates one disk
object as the primary disk object with a primary path, while the other is
designated the secondary disk object with an alternate path. If the primary path
becomes inaccessible, the software redirects the data to the secondary disk object
through the alternate path, preserving the LUN.
This redirection is known as path failover. The software continuously tries to
access the failed path by issuing a SCSI Test Unit Ready command. A good status
returned indicates the path is repaired and restored to operational status. The
software automatically redirects data back to the primary path and primary disk
object. This restoration of data transfer is known as path failback.
Fibre Channel Media Types
Optical transceivers are provided with the enclosure. Fibre optical transceivers
provides a more reliable media and supports distances up to 300 meters between
nodes.
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Alternate Path Software