Some of my customers ask about Metro Storage Cluster configuration for VMware Deployment to achieve better availability of their precious data. There is a very good resource from Duncan Epping (one of VMware most respectful technologist). One of the topic is the Requirement and Constraints from VMware technology perspective. Well, this is the explanation taken from the whitepaper.
Due to the technical constraints of an online migration of VMs, the following specific requirements, which are listed in the VMware Compatibility Guide, must be met prior to consideration of a stretched cluster implementation:
- Storage connectivity using Fibre Channel, iSCSI, NFS, and FCoE is supported.
- The maximum supported network latency between sites for the VMware ESXiTM management networks is 10ms round-trip time (RTT).
- vSphere vMotion, and vSphere Storage vMotion, supports a maximum of 150ms latency as of vSphere 6.0, but this is not intended for stretched clustering usage.
- The maximum supported latency for synchronous storage replication links is 10ms RTT. Refer to documentation from the storage vendor because the maximum tolerated latency is lower in most cases. The most commonly supported maximum RTT is 5ms.
- The ESXi vSphere vMotion network has a redundant network link minimum of 250Mbps.The storage requirements are slightly more complex. A vSphere Metro Storage Cluster requires what is in effect a single storage subsystem that spans both sites. In this design, a given datastore must be accessible—that is, be able to be read and be written to—simultaneously from both sites. Further, when problems occur, the ESXi hosts must be able to continue to access datastores from either array transparently and with no impact to ongoing storage operations.
Download the complete document from here: vmware-vsphere-metro-storage-cluster-recommended-practices-white-paper (http://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vmware-vsphere-metro-storage-cluster-recommended-practices-white-paper.pdf)