In the Storage Cluster function, the mode related to the method for failing over from the Primary Storage to the Secondary Storage is called "Failover mode". In addition, the mode related to the method for failing back from the Secondary Storage to the Primary Storage is called "Failback mode".
Failover Mode
Either of the following can be selected.
Failover Mode | Explanation |
|---|---|
Auto | This is the Failover mode that runs automatically when a failure of the Primary Storage is detected. This function that automatically performs a failover is called "Automatic Failover". |
Manual | This is the Failover mode that runs manually. |
Note
Even if the interface type of the REC path is "iSCSI", if the Primary Storage and the Secondary Storage do not support Automatic Failover through the REC path of the iSCSI port, set this mode to "Manual".
Failback Mode
Either of the following can be specified.
Mode | Explanation |
|---|---|
Auto | This is the Failback mode that runs automatically when a failure recovery of the Primary Storage is detected. This function that automatically performs a failback is called "Automatic Failback". |
Manual | This is the Failback mode that runs manually. |
Automatic Failover
"Figure 9.8 Behavior of Automatic Failover when Storage Device is downed in the Active-Active Configuration" shows an image that Storage A (Primary Storage) is down and a failover to Storage B (Secondary Storage) is performed when Storage A and Storage B are in use in the Active-Active configuration. The TFOG Role of Storage A switches from "Local" to "Remote" and the TFOG Role of Storage B switches from "Remote" to "Local" due to a failover.
"Figure 9.9 Behavior of Automatic Failover when Storage Device is downed in the Active-Standby Configuration (for FC Connection Environment)" shows an image that Storage A (Primary Storage) is down and a failover to Storage B (Secondary Storage) is performed when Storage A and Storage B are in use in the Active-Standby configuration. This is an example for FC connection environments. For iSCSI connection environments, the iSCSI name and iSCSI IP address are set for the CA port and the switch becomes the network switch.
Figure 9.8 Behavior of Automatic Failover when Storage Device is downed in the Active-Active Configuration
Figure 9.9 Behavior of Automatic Failover when Storage Device is downed in the Active-Standby Configuration (for FC Connection Environment)
"Figure 9.10 Behavior of Automatic Failover when CA Port is linked down in the Active-Active Configuration" shows an image that all the CA ports belonging to the Primary TFO group are linked down because of CA port failure or connection failure in Storage A (Primary Storage) and a failover to Storage B (Secondary Storage) is performed when Storage A and Storage B are in use in the Active-Active configuration.
"Figure 9.11 Behavior of Automatic Failover when CA Port is linked down in the Active-Standby Configuration (for FC Connection Environment)" shows an image that all the CA ports belonging to the Primary TFO group are linked down because of CA port failure or connection failure in Storage A (Primary Storage) and a failover to Storage B (Secondary Storage) is performed when Storage A and Storage B are in use in the Active-Standby configuration. This is an example for FC connection environments. For iSCSI connection environments, the iSCSI name and iSCSI IP address are set for the CA port and the switch becomes the network switch.
In accordance with link switchover of each CA port, the status of TFO group is also automatically switched, so that the volumes in the Secondary TFO group become accessible.
Figure 9.10 Behavior of Automatic Failover when CA Port is linked down in the Active-Active Configuration
Figure 9.11 Behavior of Automatic Failover when CA Port is linked down in the Active-Standby Configuration (for FC Connection Environment)
Note
When the storage device is an ETERNUS DX S4/S3 series (excluding the ETERNUS DX8900 S4) or an ETERNUS AF S2 series, or when the storage device is an ETERNUS DX8900 S4 whose firmware version is earlier than V11L20, if a Linkdown of the REC path between the Primary Storage and the Secondary Storage and a Linkdown of the CA port that connects with business servers occur at the same time when multiple switches fail, Automatic Failover cannot be performed during a CA port Linkdown. Configure the system settings to separate the switches for the REC path and for the business server so that a simultaneous Linkdown does not occur.
Automatic Failback
Automatic Failback is a function in which the Primary TFO group automatically becomes "Active" when recovering from the failure of ETERNUS Disk storage system with the Primary TFO group detected.
