Users Guide

Figure 14. High level metro node Witness architecture
Metro node Metro HA
Metro node Metro High Availability (HA) configurations consist of a metro node Metro system deployed in conjunction with
metro node Witness. There are two types of Metro HA configurations:
● Metro node Metro HA can be deployed in places where the clusters are separated by 5 ms latency RTT or less.
● Metro node Metro HA combined with Cross Connect between the metro node clusters and hosts can be deployed where the
clusters are separated by 10 ms latency RTT or less.
Metro HA (without cross-connect)
Combine metro node Metro HA with host failover clustering technologies such as VMware HA to create fully automatic
application restart for any site-level disaster.
Metro node Metro/VMware HA configurations:
● Significantly reduce the Recovery Time Objective (RTO). In some cases, RTO can be eliminated.
● Ride through any single component failure (including the failure of an entire storage array) without disruption.
● When VMware Distributed Resource Scheduler (DRS) is enabled, distribute workload spikes between data centers,
alleviating the need to purchase more storage.
● Eliminate the requirement to stretch the Fiber Channel fabric between sites. You can maintain fabric isolation between the
two sites.
In this deployment, virtual machines can write to the same distributed device from either cluster and move between two
geographically disparate locations.
If you use VMware Distributed Resource Scheduler (DRS) to automate load distribution on virtual machines across multiple ESX
servers, you can move a virtual machine from an ESX server attached to one metro node cluster to an ESX server attached to
the second metro node cluster, without losing access to the underlying storage.
Integrity and resiliency
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