Administrator Guide

Live Volume support for Microsoft Windows/Hyper-V
72 Dell EMC SC Series: Synchronous Replication and Live Volume | CML1064
9.4 Windows Server support limitations with Live Volume ALUA
Live Volume ALUA support with SCOS 7.3 and DSM 2018 R1 has use case limitations to be aware of.
In the process of developing this feature, it was found that the Microsoft implementation of MPIO incorrectly
utilizes non-optimal paths when a stretch cluster node is configured to use non-uniform server mappings to a
secondary Live Volume. In cases where no optimal paths are available, the Windows host will use a single
available non-optimal path, instead of using Round Robin to spread the I/O over all available non-optimal
paths. While a host configured to use only non-optimal paths to a secondary Live Volume (with non-uniform
server mappings) is a legitimate use-case scenario by design with Live Volume ALUA, it is not a typical
configuration encountered in the SAN industry, and this issue was not immediately apparent.
To address this limitation, install the March 2018 monthly cumulative update for Windows Server 2016.
Microsoft does not plan to extend this fix to Windows Server operating systems prior to Windows Server
2016.
Customers should consider their design and decide whether to implement Live Volume ALUA support for their
Windows Server hosts when using non-uniform server mappings with Live Volume. The following details the
support for Windows Server:
• Windows Server 2016 with the March 2018 cumulative update and newer fully supports Live Volume
ALUA.
• Windows Server 2012 R2 and prior: When using non-uniform server mappings for stretch cluster
nodes, the recommendation is to uncheck the Report Non-Optimal Paths option, and the host
server will detect and utilize all available paths as active-optimized.