4.0

Site Pairing
The protected and recovery sites must be paired before you can use SRM. Site pairing includes three main
steps:
1 Exchange of authentication information between the two sites.
2 Discovery of the replicated storage arrays that support the protected site, and discovery of peer arrays at
the recovery site.
3 Discovery of the replicated devices supported by the arrays, and mapping of these devices to datastores
that support virtual machines.
SRM includes a wizard that guides you through the site-pairing process.
Site pairing requires vSphere administrative privileges at both sites. To initiate the site-pairing process, you
must know the username and password of a vSphere administrator at each site.
Array-Based Replication
In array-based replication, one or more storage arrays at the protected site replicate data to peer arrays at the
recovery site. Storage replication adapter (SRAs) enable integration of SRM with a wide variety of replicated
arrays.
You can configure array-based replication between ESX hosts whether or not you use SRM. In fact, it is a good
idea to set up this replication before you install and configure SRM, so that you can be certain it is working
correctly before you install SRM and the necessary SRAs.
Storage Replication Adapters
Storage replication adapters are not part of an SRM release. They are developed and supported by your array
vendor. You can download storage replication adapters and their documentation from
http://www.vmware.com/download/srm/. Storage replication adapters downloaded from other sites are not
supported by VMware. You must install an SRA specific to each array that you use with SRM on the SRM
server host.
Replicated Storage Devices, Datastores, and Datastore Groups
When you use array-based replication, each storage array supports a set of replicated devices. On Storage Area
Network (SAN) arrays that use connection protocols such as Fibre Channel and iSCSI, these devices are called
LUNs (logical storage units comprising one or more physical devices). On NFS arrays, they are typically
referred to as volumes. In every pair of replicated storage devices, one device is the replication source and the
other is the replication target. Data written to the source device is replicated to the target device on a schedule
controlled by the arrays' replication software. When you configure SRM to work with an SRA, the protected
site is the replication source and the recovery site is the replication target.
A VMFS 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, SRM must ensure that all devices
in a datastore are replicated before it can protect the virtual machines that use that datastore. When necessary,
SRM aggregates datastores into datastore groups to accommodate virtual machines that span multiple
datastores. The set of virtual machines that use a replicated datastore or datastore group is called a protection
group. Any datastore that supports a protection group is considered a protected datastore.
About Bidirectional Operation
Any pair of sites can be configured to operate bidirectionally, so that each acts as a recovery site for the other.
To support bidirectional operation, you must have arrays at each site that are configured as replication targets
of the other site. This type of configuration is the only way to provide SRM services for both members of a site
pair.
Site Recovery Manager Administration Guide
8 VMware, Inc.