Administrator Guide

Live Volume support for Microsoft Windows/Hyper-V
74 Dell EMC SC Series: Synchronous Replication and Live Volume | CML1064
9.6 Uniform server mappings with Live Volume and Round Robin
In Figure 65, a Round Robin Live Volume MPIO configuration is depicted. In this scenario, the server has two
adapters and is mapped to both SC Series arrays that host the primary and secondary Live Volume pair. This
configuration is referred to as uniform server mapping since the server is mapped to both SC Series arrays.
Since all four paths are included in an MPIO Round Robin policy, about half of the storage traffic has to
traverse the proxy link between the two SC Series arrays. In cases where the two SC Series arrays are well
connected (for example, if they reside within the same data center), the slight latency penalty incurred for
proxied data may be negligible for the workload, and this design would perform well. However, this
configuration would be sub-optimal if there were significant latency or bandwidth limitations for the secondary
paths, in which case, Round Robin with Subset or Failover Only would be a better choice.
Round Robin with uniform server mappings also prevents a Live Volume from automatically swapping roles
(when the Swap Roles Automatically feature is enabled on a Live Volume) because about 50% of the traffic
will always be going through each array and therefore the thresholds that trigger a role swap will not be
exceeded.
The decision to use uniform or non-uniform server mappings in conjunction with MPIO Round Robin, Round
Robin with Subset (with non-optimal paths reported to the host server), or Failover Only is a function of
environmental variables that are unique to each customer. Because there are so many different configuration
possibilities, administrators have great flexibility to tailor a solution that is best for their environment.
Uniform server mapping with MPIO