Administrator Guide

Live Volume overview
37 Dell EMC SC Series: Synchronous Replication and Live Volume | CML1064
In Figure 33, a mapped server is accessing a Live Volume by proxy access through the secondary Live
Volume system to the primary Live Volume system. This type of proxy data access requires the replication
link between the two arrays to have enough bandwidth and minimum latency to support the I/O operations
and latency requirements of the application data access.
Proxy data access through the Secondary Live Volume
5.3 Live Volume ALUA
The Live Volume Asymmetric Logical Unit Access (ALUA) feature was added in SCOS 7.3 and DSM 2018
following the T10 SCSI-3 specification SPC-3 for Microsoft Windows, Hyper-V, and vSphere operating
systems. The feature is enabled on a per-Live-Volume basis and allows the advertisement of MPIO paths to
the primary Live Volume as optimal and MPIO paths to the secondary Live Volume as non-optimal. When
used in conjunction with an ALUA-supporting Round Robin path selection policy (PSP), optimal paths will be
used for read and write I/O when available while non-optimal paths will be reserved for use in the event no
optimal paths are available. If a Live Volume role swap or Automatic Failover occurs, the SC Series array will
report the ALUA path state changes to the storage host upon request. The feature effectively allows a Round
Robin PSP to be used with Live Volume in either uniform or non-uniform storage presentations. The Round
Robin PSP is easy to deploy, requires minimal administrative effort and documentation, and yields a good
balance of storage port, fabric, and controller utilization.