Storage Cluster; Figure 72 Storage Cluster - Fujitsu ETERNUS DX100 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 storage. 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 pos-
sible 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 cre-
ated by mirroring 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 72 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 DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems Design Guide (Basic)
Business server
SAN
Failover
CA
Device
failure
Primary storage
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Storage Cluster
controller
I/O
CA
Secondary storage
LAN
ETERNUS DX/AF
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