HP Surestore Auto Path Virtual Array for Windows NT Installation and User's Guide

6 HP Auto Path XP: User’s Guide (Windows NT/2000)
Auto Path description
The HP Auto Path software performs dynamic load balancing of data flow
through multiple paths. It detects multiple paths to each logical device and
distributes the data load among the paths for optimum performance. It
automatically detects path failures and switches to alternate paths and also
recovers the failed paths after they are restored.
The user interface lets a system administrator define load balancing policies
and preferred paths, and view device path information. Auto Path manages
paths according to the balancing policy, ensuring that no single path is a
performance bottleneck.
Normally, disk I/O is sent directly to the disk driver. Auto Path is a filter
driver that fits between the Windows disk driver and the host bus adapter
(HBA) driver (figure 1). Auto Path is transparent to the Windows operating
system and to the applications running on a server.
Figure 1. I/O Flow
The Auto Path GUI consists of two software components:
• server
The server component runs on the host that is connected to the disk
array.
• client
The client can run either on the host or from a remote PC connected
through the network.
System disk I/O Windows disk driver
Auto Path
Adapter driver
driver
LUN