Glossary of MetroCluster terms

aggregate

A grouping of physical storage resources (disks or array LUNs) that provides storage to volumes associated with the aggregate. Aggregates provide the ability to control the RAID configuration for all associated volumes.

data SVM

Formerly known as data Vserver. In clustered Data ONTAP, a Storage Virtual Machine (SVM) that facilitates data access from the cluster; the hardware and storage resources of the cluster are dynamically shared by data SVMs within a cluster.

admin SVM

Formerly known as admin Vserver. In clustered Data ONTAP, a Storage Virtual Machine (SVM) that has overall administrative access to all objects in the cluster, including all objects owned by other SVMs, but does not provide data access to clients or hosts.

inter-switch link (ISL)

A connection between two switches using the E-port.

destination

The storage to which source data is backed up, mirrored, or migrated.

disaster recovery (DR) group

The four nodes in a MetroCluster configuration that synchronously replicate each others' configuration and data.

disaster recovery (DR) partner

A node's partner at the remote MetroCluster site. The node mirrors its DR partner's NVRAM or NVMEM partition.

disaster recovery auxiliary (DR auxiliary) partner

The HA partner of a node's DR partner. The DR auxiliary partner mirrors a node's NVRAM or NVMEM partition in the event of an HA takeover after a MetroCluster switchover operation.

HA pair

In Data ONTAP 8.x, a pair of nodes whose controllers are configured to serve data for each other if one of the two nodes stops functioning.
Depending on the system model, both controllers can be in a single chassis, or one controller can be in one chassis and the other controller can be in a separate chassis.
In the Data ONTAP 7.3 and 7.2 release families, this functionality is referred to as an active/active configuration.

HA partner

A node's partner within the local HA pair. The node mirrors its HA partner's NVRAM or NVMEM cache.

high availability (HA)

In Data ONTAP 8.x, the recovery capability provided by a pair of nodes (storage systems), called an HA pair, that are configured to serve data for each other if one of the two nodes stops functioning. In the Data ONTAP 7.3 and 7.2 release families, this functionality is referred to as an active/active configuration.

healing

The two required MetroCluster operations that prepare the storage located at the DR site for switchback. The first heal operation resynchronizes the mirrored plexes. The second heal operation returns ownership of root aggregates to the DR nodes.

LIF (logical interface)

A logical network interface, representing a network access point to a node. LIFs currently correspond to IP addresses, but could be implemented by any interconnect. A LIF is generally bound to a physical network port; that is, an Ethernet port. LIFs can fail over to other physical ports (potentially on other nodes) based on policies interpreted by the LIF manager.

NVRAM

nonvolatile random-access memory.

NVRAM cache

Nonvolatile RAM in a storage system, used for logging incoming write data and NFS requests. Improves system performance and prevents loss of data in case of a storage system or power failure.

NVRAM mirror

A synchronously updated copy of the contents of the storage system NVRAM (nonvolatile random access memory) contents kept on the partner storage system.

node

In Data ONTAP, one of the systems in a cluster or an HA pair.
To distinguish between the two nodes in an HA pair, one node is sometimes called the local node and the other node is sometimes called the partner node or remote node.
In Protection Manager and Provisioning Manager, the set of storage containers (storage systems, aggregates, volumes, or qtrees) that are assigned to a dataset and designated either primary data (primary node), secondary data (secondary node), or tertiary data (tertiary node).
A dataset node refers to any of the nodes configured for a dataset.

A backup node refers to either a secondary or tertiary node that is the destination of a backup or mirror operation.

A disaster recovery node refers to the dataset node that is the destination of a failover operation.

remote storage

The storage that is accessible to the local node, but is at the location of the remote node.

root volume

A special volume on each Data ONTAP system. The root volume contains system files and configuration information, and can also contain data. It is required for the system to be able to boot and to function properly. Core dump files, which are important for troubleshooting, are written to the root volume if there is enough space.

switchback

The MetroCluster operation that restores service back to one of the MetroCluster sites.

switchover

The MetroCluster operation that transfers service from one of the MetroCluster sites.

A negotiated switchover is planned in advance and cleanly shuts down components of the target MetroCluster site.
A forced switchover immediately transfers service; the shut down of the target site might not be clean.