When configuring your Ready Solution with SRDF/Metro, follow these Dell EMC- and VMware-recommended best practices:
- Configure the front end with a stretched layer 2 network so that when a VM moves between sites, its IP address stays the same.
- If you want site high availability, configure two or more ESXi hosts at each site. Ensure that vSphere HA and Distributed Resource Scheduler (DRS) are active and that VM monitoring is activated.
Note: If an ESXi host fails, vSphere HA powers on the SAP VMs according to the VM restart priority. ASCS has the highest priority followed by the database, followed in turn by the application servers.
- Use host affinity rules. Host affinity rules keep VMs running in the preferred site as long as possible, only moving them to the nonpreferred site if they cannot run in the preferred site. Also use affinity rules to control VM placement and ensure that the SAP database and ASCS instances are running on separate hosts at all times.
- Use affinity rules to ensure that Oracle database VMs are running on processor cores that are fully licensed for Oracle in VMware environments. For more information, see Understanding Oracle Certification, Support and Licensing for VMware Environments on the VMware website.
- Ensure that the server resources exist to fail over to a single site. Configure admission control of vSphere HA for 50 percent CPU and 50 percent memory.
- Configure heartbeat mechanisms, which vSphere HA uses to validate the state of a host, as follows:
- Network (primary), which pings the default gateway—Specify a minimum of two additional isolation addresses. Configure these addresses in the Advanced Options section using the name das.isolationAddress.x (x is incremented for each address).
- Datastore (secondary)―Increase the number of heartbeat data stores from two to four in a stretched cluster environment. Configure the data stores in the Advanced Options section.
- Change the Disk.PathEvalTime on each ESXi host from 300 s to 30 s to avoid the need to manually rescan after presenting the R2 devices.
- Enable VM Component Protection (VMCP) to take advantage of new capabilities around All Paths Down (APD) and Permanent Device Loss (PDL).
To enable VMCP, check the Protect against Storage Connectivity Loss option. Then, in the Failure conditions and VM response list box under the vSphere HA Cluster setting, select Power off and restart VMs for:
- Response for Datastore with PDL
- Response for Datastore with APD
- Use a witness instead of a bias with SRDF/Metro to provide the best availability.
For more information, see VMware vSphere Metro Storage Cluster Recommended Practices on the VMware website.