Product Description; How Failover Works - HP e3000 MPE/iX Manual

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Product Description

Once installed and configured, the HAFO software is intended to provide
continued data access to supported high availability storage arrays under a
variety of conditions. There are typically five "points of failure" in any I/O
subsystem. They are:
1. Disk drive mechanisms
2. Disk power supply
3. Disk array controller
4. I/O host adapter card
5. Cabling and FC switches.
High availability storage arrays protect against the first two points of failure by
having:
•
•
The HAFO software, working in conjunction with the proper hardware
configuration and a disk storage array's ability to allow multiple interfaces to the
same LUN, provides protection for the remaining three points of failure:
•
•
•
It is important to realize that HAFO Software cannot protect you from every
type of I/O system failure. Among conditions that are not covered by HAFO are
conditions that lead to most MPE/iX System Aborts and HP e3000 High/Low
Priority Machine Checks (HPMC). These are handled outside the scope of the
I/O system and thus are outside the scope of HAFO. Fortunately, these events
should be rare as compared to the conditions HAFO does protect you from.

How Failover Works

Once installed and configured, the HAFO software continually monitors the
configured "primary path" for I/O timeouts or errors caused by component
failures. This adds minimal overhead to the I/O subsystem operation.
RAID configured disk drives (1)
Redundant power supplies (2)
Disk array controller (3)
I/O host adapter card (4)
Cabling and FC switches. (5)
Product Description
How Failover Works
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