High Availability FailOver/iX Manual (32650-90911)

Product Description
User Notification of Failover
HAFO event information and data structures are memory resident. This
eliminates the need for disk file access to perform high availability failover. This
is an advantage especially if the path should fail to Ldev#1.
To configure and manage the HAFO functions there is a new section of the
SYSGEN program for HAFO called "HA" (short for HAUTIL). The "ha"
section is accessed through SYSGEN’s "io" menu. That is, you run SYSGEN,
type "io" at the SYSGEN prompt, then type "ha" at the "io" prompt. No failover
action is taken until the Ldevs are configured for HAFO in the "ha" section of
SYSGEN. Device data path and alternate data path information is entered and
saved in SYSGEN's HAFOCONF configuration file. HAFOCONF configurations
are read and validated during each subsequent system boot. Specific
configuration information is provided in the Chapter 4, "Configuration."
Figure 2-1 illustrates a sample configuration. This figure can be compared
against Figure 2-2, which illustrates a failover of the same system.
Figure 2- 1 Normal System Layout
103
102
101
31
bus
SCSI
FC
bus
SCSI
FC
30
1
A
r
r
a
y
C
o
n
t
A
r
r
a
y
C
o
n
t
D
A
D
A
High Availability Array
MPE/iX
Å Logical Physical Æ
(view)
D
A
M
D
A
M
Ldev 103
DM
Ldev 101
DM
Ldev 31
DM
Ldev 102
DM
Ldev 30
DM
Ldev 1
DM
File
System
Volume
Mgmt
Triggering a Failover
HAFO acts on only specific error types that indicate a data path failure. Any of
these three occurrences will generate a failover:
•
Hung I/O
•
Failed high availability array controller (communicated by a SCSI reply status)
•
Failed host device adapter card
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