Administrator Guide

Failover Behavior
Legacy mode, ALUA port mode, and virtual port mode behave dierently during failure conditions because they use dierent mechanisms
to provide fault tolerance.
Table 12. Front-End I/O Ports Failover Behavior
Scenario Virtual Port Mode Legacy Mode ALUA Port Mode
Normal operating
conditions
All ports are active and pass I/O.
• Primary ports pass I/O.
• Reserved ports remain in a
standby mode until a controller
failure.
• Active/Optimized ports pass
I/O.
• Standby ports remain in a
standby mode until a controller
or port failure.
A controller fails in a dual-
controller Storage Center
Virtual ports on the failed
controller move to physical ports
on the functioning controller.
Primary ports on the failed
controller fail over to reserved
ports on the functioning controller.
Active/Optimized ports on the
failed controller fail over to the
Standby ports on the functioning
controller.
A single port fails (single- or
dual-controller Storage
Center)
An individual port fails over to
another port on the same
controller in the same fault
domain.
NOTE: To support port
level failover, a controller
must have at least two
ports in the same fault
domain using the same
transport media, such as
FC or iSCSI.
The port does not fail over
because there was no controller
failure. If a second path is available,
MPIO software on the server
provides fault tolerance.
The port fails over to the Standby
port on the functioning controller.
Rebalancing Front-End Ports
If a controller has been added or taken oine, ports can become unbalanced. If local ports are unbalanced, you are prompted to balance
the ports by a message at the top of the Summary tab.
About this task
NOTE
: Front-end ports are automatically rebalanced when using SCv2000 and SCv3000 series controllers. Manual port
rebalance is not necessary.
Steps
1 If the Storage Manager Client is connected to a Data Collector, select a Storage Center from the Storage view.
2 Click the Summary tab.
3 In the banner message, click Rebalance Ports. The Rebalance Ports dialog box appears to display progress, and closes when the
rebalance operation is compete.
Managing Front-End I/O Port Hardware
Front-end FC and iSCSI ports can be renamed and monitored with threshold denitions. iSCSI ports can be assigned network conguration
and tested for network connectivity.
For a Storage Center in virtual port mode, the Hardware tab displays a virtual port for each physical port. For physical ports, the physical
identity, speed, and hardware are given. For virtual ports, the current and preferred physical ports are shown.
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Storage Center Maintenance