Chapter 7. Highly Available controller pairs 75
Table 7-1 Configuration types
Certain terms have the following particular meanings when they are used to refer to HA pair
configuration:
An
HA pair configuration is a pair of storage systems that are configured to serve data for
each other if one of the two systems becomes impaired. In Data ONTAP documentation
and other information resources, HA pair configurations are sometimes also called
HA
pairs
.
When a system is in an HA pair configuration, systems are often called
nodes. One node is
sometimes called the
local node, and the other node is called the partner node or remote
node
.
Controller failover, which is also called cluster failover (CFO), refers to the technology
that enables two storage systems to take over each other’s data. This configuration
improves data availability.
FC direct-attached topologies are topologies in which the hosts are directly attached to
the storage system. Direct-attached systems do not use a fabric or Fibre Channel
switches.
FC dual fabric topologies are topologies in which each host is attached to two physically
independent fabrics that are connected to storage systems. Each independent fabric can
consist of multiple Fibre Channel switches. A fabric that is zoned into two logically
independent fabrics is not a dual fabric connection.
FC single fabric topologies are topologies in which the hosts are attached to the storage
systems through a single Fibre Channel fabric. The fabric can consist of multiple Fibre
Channel switches.
iSCSI direct-attached topologies are topologies in which the hosts are directly attached to
the storage controller. Direct-attached systems do not use networks or Ethernet switches.
HA pair
configuration
type
If A-SIS
active
Distance between
nodes
Failover possible
after loss of entire
node (including
storage)
Notes
Standard HA pair
configuration
No Up to 500 meters
a
a. SAS configurations are limited to 5 meters between nodes
No Use this configuration to provide
higher availability by protecting
against many hardware single
points of failure.
Mirrored HA pair
configuration
Yes Up to 500 meters
a
No Use this configuration to add
increased data protection to the
benefits of a standard HA pair
configuration.
Stretch
MetroCluster
Yes Up to 500 meters
(270 meters if Fibre
Channel speed 4 Gbps
and 150 meters if Fibre
Channel speed is 8
Gbps)
Yes Use this configuration to provide
data and hardware duplication
to protect against a local
disaster.
Fabric-attached
MetroCluster
Yes Up to 100 km depending
on switch configuration.
For gateway systems, up
to 30 km.
Yes Use this configuration to provide
data and hardware duplication
to protect against a larger-scale
disaster.
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