6.1

A datastore provides storage for virtual machine files. By hiding the details of physical storage devices,
datastores simplify the allocation of storage capacity and provide a uniform model for meeting the storage
needs of virtual machines. Because any datastore can span multiple devices, Site Recovery Manager must
ensure that all devices backing the datastore are replicated before it can protect the virtual machines that use
that datastore. Site Recovery Manager must ensure that all datastores containing protected virtual machine
files are replicated. During a recovery or test, Site Recovery Manager must handle all such datastores
together.
To achieve this goal, Site Recovery Manager aggregates datastores into datastore groups to accommodate
virtual machines that span multiple datastores. Site Recovery Manager regularly checks and ensures that
datastore groups contain all necessary datastores to provide protection for the appropriate virtual machines.
When necessary, Site Recovery Manager recalculates datastore groups. For example, this can occur when
you add new devices to a virtual machine, and you store those devices on a datastore that was not
previously a part of the datastore group.
A datastore group consists of the smallest set of datastores required to ensure that if any of a virtual
machine's files is stored on a datastore in the group, all of the virtual machine's files are stored on datastores
that are part of the same group. For example, if a virtual machine has disks on two different datastores, then
Site Recovery Manager combines both datastores into a datastore group. Site Recovery Manager combines
devices into datastore groups according to set criteria.
n
Two different datastores contain files that belong to the same virtual machine.
n
Datastores that belong to two virtual machines share a raw disk mapping (RDM) device on a SAN
array, as in the case of a Microsoft cluster server (MSCS) cluster.
n
Two datastores span extents corresponding to different partitions of the same device.
n
A single datastore spans two extents corresponding to partitions of two different devices. The two
extents must be in a single consistency group and the SRA must report consistency group information
from the array in the device discovery stage. Otherwise, the creation of protection groups based on this
datastore is not possible even though the SRA reports that the extents that make up this datastore are
replicated.
n
Multiple datastores belong to a consistency group. A consistency group is a collection of replicated
datastores where every state of the target set of datastores existed at a specific time as the state of the
source set of datastores. Informally, the datastores are replicated together such that when recovery
happens using those datastores, software accessing the targets does not see the data in a state that the
software is not prepared to deal with.
Protecting Virtual Machines on VMFS Datastores that Span Multiple LUNs or
Extents
Not all SRAs report consistency group information from the storage array, because not all storage arrays
support consistency groups. If an SRA reports consistency group information from the array following a
datastore discovery command, the LUNs that constitute a multi-extent VMFS datastore must be in the same
storage array consistency group. If the array does not support consistency groups and the SRA does not
report any consistency group information, Site Recovery Manager cannot protect virtual machines located
on the multi-extent datastore.
About vSphere Replication Protection Groups
You can include virtual machines that you configured for vSphere Replication in vSphere Replication
protection groups.
Virtual machines in the vCenter Server inventory that are configured for vSphere Replication are available
for selection when you create or edit a vSphere Replication protection group.
Chapter 5 Creating and Managing Protection Groups
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