The example of structure between both the Primary Storage and the Secondary Storage and Storage Cluster Controller is shown in "Figure 9.12 Structure Example of Life Check via Storage Cluster Controller". In this structure example, communication status, device status and timing of Automatic Failover are shown in "Table 9.8 Timing of Automatic Failover Operation".
Figure 9.12 Structure Example of Life Check via Storage Cluster Controller
Number | Communication Status | Device Status | ||||
|---|---|---|---|---|---|---|
(1) | (2) | (3) | Primary Storage | Secondary Storage | Timing of Automatic Failover Operation and Status Change | |
1 | Y | Y | Y | Alive | Alive | N/A |
2 | N | Y | Y | |||
3 | Y | N | Y | |||
4 | Y | Y | N | |||
5 | N | N | Y | Down | A Primary Storage: Active -> Standby | |
6 | N | Y | N | Alive | Down | N/A |
7 | Y | N | N | Alive | ||
8 | N | N | N | Down | Down | N/A (all blocked) (*1) |
Y: Communication enabled status
N: Communication disabled status
*1: During a disaster, when recreating a network environment that includes communication of Storage Cluster Controller, the communication from Storage Cluster Controller may be temporarily disconnected and an overall blockage may occur.
Note
Automatic Failover does not operate in the following cases:
For FC connection environments
When "route (1) between the Primary Storage and the Secondary Storage" failed 10 seconds after "route (2) between the Primary Storage and the Storage Cluster Controller" had failed.
When "route (2) between the Primary Storage and the Storage Cluster Controller" failed three seconds after "route (1) between the Primary Storage and the Secondary Storage" had failed.
For iSCSI connection environments
When "route (1) between the Primary Storage and the Secondary Storage" failed 20 seconds after "route (2) between the Primary Storage and the Storage Cluster Controller" had failed.
When "route (2) between the Primary Storage and the Storage Cluster Controller" failed seven seconds after "route (1) between the Primary Storage and the Secondary Storage" had failed.
Location of Storage Cluster Controller
Storage Cluster Controller and each monitored ETERNUS Disk storage system monitor each other. Therefore, if the Storage Cluster Controller and the managed ETERNUS Disk storage systems are placed in the same building, the following trouble could occur:
If the building is exposed to disaster, all the paths are blocked and failover gets disabled.
To prevent the above trouble, it is recommended to place the Storage Cluster Controller and each monitored ETERNUS Disk storage system in separate buildings respectively. The location example is shown in "Figure 9.13 Location Example of Storage Cluster Controller and Monitored ETERNUS Disk Storage Systems". Also, the Storage Cluster Controller can be located on the same server as Management Server.
Figure 9.13 Location Example of Storage Cluster Controller and Monitored ETERNUS Disk Storage Systems
