Administrator Guide

Synchronous replication use cases
30 Dell EMC SC Series: Synchronous Replication and Live Volume | CML1064
resync login accounts). For VMware vSphere and Hyper-V hosts, VM datastores are now visible to the hosts
and VMs need to be added to the inventory so that they can be allocated as compute and storage resources
by the hypervisor and then powered on.
In Hyper-V 2008 R2, the configuration file for each virtual machine must be generated with the correct number
of processors, memory, network card, and attached virtual machine disk files. This is a process that is
documented or scripted prior to the DR event. Hyper-V 2012/R2 and newer includes a virtual machine import
wizard that is able to import the existing virtual machine configuration located on replicated Dell storage,
rather than generating a new configuration for each VM from scratch. Once the VMs are added to inventory in
Hyper-V 2008 R2 or Hyper-V 2012/R2 and newer, they can be powered on. All versions of VMware vSphere
have the same capability as Hyper-V 2012/R2 and newer in that once datastores are presented to the
vSphere hosts, the datastores can be browsed and the virtual machine configuration file that is located in
each VM folder can be added to inventory and then powered on. A manual DR process, especially in an
environment with hundreds or thousands of virtual machines, quickly eats into RTO. The automation of
discovering and adding virtual machines to inventory is covered in the next section.
VMware vSphere Site Recovery Manager is a disaster recovery and planned migration tool for virtual
machines. It bolts onto an existing vSphere environment and leverages Dell Technologies™ certified storage
and array-based replication. Both synchronous and asynchronous replication are supported as well as each
of their native features. Live Volume stretched storage is also supported in specific configurations starting with
SRM 6.1. With this support, customers can strive for RPOs that are more aggressive and maintain
compatibility with third party automation tools, like SRM, to maintain RTOs in large VMware virtualized
environments.
For vSphere environments, SRM invokes the commands necessary for tasks (such as managing replication,
creating snapshots, creating view volumes, and presenting and removing volumes from vSphere hosts) to be
performed at the storage layer without removing DSM from the architecture. The storage-related commands
from SRM flow to the Storage Replication Adapter (SRA) and then to the DSM server. For this reason, a DSM
Data Collector needs to remain available at the recovery site for the automation to be carried out. Outside of
SRM, in a heterogeneous data center, DSM or API scripting would be needed to carry out the DR automation
for Hyper-V or physical hosts.
Beyond the scope of storage, SRM automates other processes of DR testing, DR recovery, and planned
migrations, making it a major contributor to meeting RTO goals. SRM takes care of important, time-
consuming tasks such as adding virtual machines to inventory at the DR site, modifying TCP/IP address
configurations, VM dependency, power-on order, and reprotection of virtual machines.