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2. Basic Functions
Stable Operation
The following table provides the function specifications for the Storage Cluster.
Table 44
Storage Cluster Function Specifications
Item
Number of connectable storage systems
Business server connections
Copy path (connection between storage systems)
Maximum configurable capacity (per storage system) (*1)
Maximum number of TFO groups (per storage system)
Failover
Failback
Automatic failover triggers
Storage Cluster Continuous Copy (*2)
¡: Possible, ´: Not possible
*1: The total available capacity of TFOVs for an ETERNUS AF/DX can be expanded by setting an expansion for the total capacity of TFOVs. If
the installed memory is not sufficient, the expansion setting cannot be performed.
For details on setting an expansion for the total capacity of TFOVs, refer to "ETERNUS CLI User's Guide".
*2: Storage Cluster Continuous Copy is an ETERNUS AF/DX function that performs a copy on the Primary storage and the Secondary storage
simultaneously, and achieves consistency between the two storage systems. This is achieved by operating Advanced Copy from a TFOV to
a TFOV.
Caution
• After an error occurs in the Primary storage or RAID group, while the Primary storage is being switched
to the Secondary storage (max. 10 seconds), the Primary and Secondary storage cannot be accessed.
Therefore, business applications are expected to have a maximum I/O delay response of 10 seconds.
• Data mirroring between the Primary storage and the Secondary storage is performed by the Storage
Cluster during normal operations. When a write is performed from the server to the Primary storage,
data is also transferred to the Secondary storage, and after the transfer is complete a write completion is
responded to the server. Therefore, when the Storage Cluster is installed, the response degrades during
a write compared to an environment without the Storage Cluster.
• Using OPC or QuickOPC for Advanced Copy from a TFOV is recommended.
• In environments that use an iSCSI configuration, a switchover of the storage systems that is required for
a failover or a failback takes from 30 seconds to 120 seconds to be complete. Server I/O must also be
restarted in some cases.
• The connection interface of business servers is FC or iSCSI (cannot be mixed). In addition, the switch
connection topology is supported.
• For details on the required environment for the Storage Cluster (OS, HBA, multipath driver, and cluster
software), refer to "Support Matrix".
Automatic
Manual
Automatic
Manual
ETERNUS AF/DX failure
Power failure/shutdown
RAID failure/RAID blockage
CA port link down
114
Specifications
1
Switch connections only
Direct connection and remote connection
2,048TB (ETERNUS AF150 S3/AF250 S3)
8,192TB (ETERNUS AF650 S3)
32
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