Home > Workload Solutions > SAP > Guides > SAP HANA TDI Guides > Dell Validated Design for SAP HANA TDI with Dell PowerStore Storage > Implementing STONITH with the HA/DR provider for SAP HANA
Note: This section applies only to multihost SAP HANA scale-out instances on NAS and the host autofailover.
On failover, the database on the standby host must have read-access and write-access to the files of the failed active host. If the failed host can still write to these files, the files might become corrupted. Preventing this corruption is called “fencing.” When you use shared file systems such as PowerStore NAS storage and NFSv3 or NFSv4, the STONITH method is implemented to achieve proper fencing capabilities and ensure that locks are always freed.
Note: For multihost SAP HANA scale-out instances and the host autofailover with NFSv3, the STONITH (SAP HANA HA/DR provider) implementation is mandatory. With NFSv4, a locking mechanism based on lease-time is available. The locking mechanism can be used for I/O fencing, and STONITH is not required. However, STONITH can be used to speed up failover and ensure that locks are always released.
In such a setup, the storage connector API can be used for invoking the STONITH calls. During failover, the SAP HANA leading host calls the STONITH method of the custom storage connector with the hostname of the failed host as the input value.
A mapping of hostnames to management network addresses is maintained, which is used to send a reboot signal to the server through the management network. When the host restarts, it automatically starts in a standby host role. The STONITH example uses the Intelligent Platform Management Interface (IPMI) in bare-metal deployments with Dell PowerEdge servers.