View source for VMworld 2015/Building a Stretched Cluster with Virtual SAN

== Building a Stretched Cluster with Virtual SAN ==

By Duncan Epping and Rawlinson Rivera (VMware)

“A stretched cluster is a deployment model in which two or more virtualization host servers are part of the same logical cluster but are located in separate geographical locations.”

Metro Clusters

vSphere + Virtual SAN – Stretched Cluster

Fault Domains – (data, data, witness)

Virtual SAN cluster is formed across the 3 fault domains (sites or datacenters)

Requirements:
*	Network:
**	Virtual SAN storage networking
**	Virtual SAN witness networking
**	vSphere and virtual machine networking
**	10 Gbps connectivity or greater
**	< 5 millisecond latency RTT
**	Multicasting
*	Storage:
**	Virtual machine storage
**	Witness appliance storage
*	Compute:
**	Virtual SAN witness
**	vSphere HA
**	vSphere DRS

Witness only stores metadata.  Communication to it is minimal.


Steps to build a stretch cluster:
*	Configure Fault Domains
*	Select Witness Host
*	?
*	?

Virtual Machine Monitoring – the core of the heart beating for HA
*	If doing maintenance, disable this

Reserved failover capacity resources – set to 50% (yes you lose half your resources!)

Test Test Test - Test all of the various failure scenarios you can have
* Network partition between data sites
* Full site failure
* Witness site failure

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