Storage Cluster; Figure 75 Storage Cluster - Fujitsu ETERNUS DX500 S4/DX600 S4 Design Manual

3. SAN Functions
Stable Operation via Load Control

Storage Cluster

Storage Cluster is a function that allows continuous operations by using redundant connections to two ETERNUS
DX/AF storage systems so that even if the Primary storage fails, operations are switched to the Secondary stor-
age. Operations can continue without stopping access from the server if there are unexpected problems or if the
storage system is in an error state due to severe failures.
Volumes that are accessed from business servers remain accessible with the same drive or mount point even
after switching to the ETERNUS DX/AF. Transparent access from business servers is possible even after switching
to the ETERNUS DX/AF. Reallocating volumes or switching mount points is not required.
Storage Cluster is set for each logical volume. A paired configuration for the target volume is created by mirror-
ing between ETERNUS DX/AF storage systems.
If a failover occurs during operation, a link down error occurs in the CA port on the Primary storage, and the CA
port on the Secondary storage takes over. A maximum of 10 seconds is required for the automatic switchover,
but operations can continue with the server's I/O retry.
To use Storage Cluster, the ETERNUS SF Storage Cruiser Storage Cluster option is necessary.

Figure 75 Storage Cluster

ETERNUS DX/AF
For Storage Cluster settings, create TFO groups that include target volumes (TFOV), and specify the connection
configuration and the policy for each group.
FUJITSU Storage ETERNUS DX500 S4/DX600 S4, ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Design Guide (Basic)
Business server
SAN
I/O
Failover
CA
Device
failure
Primary storage
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Storage Cluster
controller
CA
Secondary storage
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LAN
ETERNUS DX/AF
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