IBM N Series - Eliminating Single Points of Failure with HA Pair Configurations

88 IBM System Storage N series Hardware Guide
5. Give back the partner node by entering the following command:
cf giveback
The local node releases the partner node, which reboots and resumes normal operation.
The following message is displayed on the console when the process is complete:
giveback completed
6. Proceed as shown in Table 7-3, depending on whether you received the message that
giveback was completed successfully.
Table 7-3 Takeover and giveback messages
7.3.8 Eliminating single points of failure with HA pair configurations
Table 7-4 lists the ways that the use of HA pair configurations helps you to avoid SPOFs in
various hardware components.
Table 7-4 Avoiding SPOFs by using HA pair configurations
If takeover and giveback Then
Is completed successfully Repeat steps 2 - 5 on the partner node.
Fails Attempt to correct the takeover or giveback failure.
Hardware
component
SPOF SPOF eliminated
Non-HA
pair
HA pair
IBM System Storage
N series storage
system
Yes No If a storage system fails, cluster failover automatically fails
over to its partner storage system and serves data from the
takeover system.
NVRAM Yes No If an NVRAM adapter fails, cluster failover automatically fails
over to its partner storage system and serves data from the
takeover storage system.
Processor fan Yes No If the processor fan fails, the node gracefully shuts down.
Cluster failover automatically fails over to its partner storage
system and serves data from the takeover storage system.
Multiple NICs with
VIFS (virtual
interfaces)
No No If one of the networking links fails, the networking traffic is
automatically sent over the remaining networking links on the
storage system. No failover is needed in this situation.
If all NICs fail, you can start failover to a partner storage
system and serve data from the takeover storage system.
Tip: Always use multiple NICs with VIFS to improve
networking availability for both single storage systems and
HA pair storage systems.
Single NIC Yes No If a NIC fails, you can start a failover to its partner storage
system and serve data from the takeover storage system.
FC-AL card Yes No If an FC-AL card for the primary loop fails, the partner node
attempts a failover at the time of failure.
If the FC-AL card for the secondary loop fails, the failover
capability is disabled. However, both storage systems
continue to serve data to their respective applications and
users, with no effect or delay.