What is vSphere Replication & how does it help in disaster recovery in Virtual Machines?

VMware vSphere Replication is a hypervisor-based, asynchronous replication solution for vSphere virtual machines. It is fully integrated with VMware vCenter Server and the vSphere Web Client. vSphere Replication delivers flexible, reliable and cost-efficient replication to enable data protection and disaster recovery for all virtual machines in your environment.

Use Cases

Data protection locally, within a single site
Disaster recovery and avoidance between two sites
Disaster recovery and avoidance to a service provider cloud
Data center migration

vSphere Replication at Work

Build Flexible Configurations

vSphere Replication provides flexible recovery options, ensures consistent application and virtual machine data, and it integrates with the VMware product stack. vSphere Replications allows you to:

Customize the recovery point objective (RPO) from 5 minutes to 24 hours
Use multiple point-–in-time (MPIT) recovery to revert to previous known states
Protect up to 2,000 virtual machines per vCenter Server environment
Use Microsoft Volume Shadow Copy Service (VSS)
Use Linux file system quiescing
Automate cross-site disaster recovery with VMware Site Recovery Manager
Protect virtual machines in the cloud using VMware vCloud Air Disaster Recovery service
Protect and recover virtual machines on VMware vSAN
Protect and recover virtual machines on vSphere Virtual Volumes datastores

Eliminate Storage Lock-In

vSphere Replication is a hypervisor-based replication solution that operates at the individual virtual machine disk (VMDK) level, allowing replication of individual virtual machines between heterogeneous storage types supported by vSphere. Because vSphere Replication is independent of the underlying storage, it works with a variety of storage types including VMware vSAN, vSphere Virtual Volumes, traditional SAN, network-attached storage (NAS), and direct-attached storage (DAS). This allows you to:

Use differing storage technologies at linked sites, such as in SAN-to-vSAN and Fibre Channel (FC)-to-Internet Small Computer System Interface (iSCSI) arrangements
Repurpose older storage at the recovery site to reduce cost
Use secondary storage only for protected virtual machines, not the entire environment

Reduce Network Bandwidth

vSphere Replication copies only changed data to the recovery site to lower bandwidth utilization, improve network efficiency and enable more aggressive RPOs than a manual, full-system copy. With vSphere Replication, you can:

Utilize a “seed copy” of virtual machine data for the initial synchronization to reduce the amount of time required to create the initial copy
Ensure efficient network utilization by tracking changed disk areas and replicating only those changes
Optionally enable data compression to further reduce network bandwidth consumption

Technical Details

Hypervisor-Based Virtual Machine Replication

vSphere Replication is a deeply integrated VMware vSphere component. It is a robust hypervisor-based virtual machine replication engine. Changed data in virtual machine disks for a running virtual machine at a primary site is sent to a secondary site. There, the changes are applied to the virtual machine disks of the offline copy (replica) of the virtual machine.

Replication Management

vSphere Replication includes an agent built into vSphere and one or more virtual appliances deployed using vSphere Web Client. The agent tracks and sends changed data from a running virtual machine to a vSphere Replication appliance at a remote site; the appliance then adds the replicated data to the offline replica copy for that virtual machine. The vSphere Replication virtual appliance also manages and monitors the replication process. This gives administrators visibility into virtual machine protection status and the ability to recover virtual machines with a few clicks.

Replication Configuration

It’s easy to configure replication for up to 2,000 virtual machines using vSphere Web Client: select one or more virtual machines, right-click on a virtual machine, and define the RPO and destination for its replica. vSphere Replication will then replicate data to meet the RPO at all times, ensuring that virtual machine content never ages past its defined replication policy. RPOs range from 5 minutes to 24 hours and can be configured on a per-virtual machine basis.

Virtual Machine Synchronization and Seed Copies

vSphere Replication can do an initial full synchronization of the source virtual machine and its replica copy. If desired, a seed copy of data can be placed at the destination to minimize the time and bandwidth required for the first replication. A seed copy of a virtual machine consists of a virtual machine disk file that can be positioned at the target location. A seed copy is manually created and placed at the recovery location using any mechanism the administrator chooses, such as offline copying, FTP, an ISO image or a virtual machine clone.

Intelligent Transfers

After the initial full synchronization is complete, vSphere Replication will transfer only changed data. The vSphere kernel tracks unique writes to protected virtual machines, identifying and replicating only those blocks that have changed between replication cycles. This keeps network traffic to a minimum and allows for aggressive RPOs.

Non-Intrusive Replication

The virtual machine replication process is non-intrusive and takes place independent of the operating system or applications in the virtual machine. It is transparent to protected virtual machines and requires no changes to their configuration or ongoing management.

Configure Replication

Recovery Settings

FAQ

Find answers to some of the most frequently asked questions about vSphere Replication.

How does vSphere Replication work?

vSphere Replication protects data and enables disaster recover (DR) for all your virtual machines, through flexible and reliable replication. It is fully integrated with vCenter Server and vSphere Web Client, providing host-based, asynchronous replication of virtual machines. It is a feature of the vSphere platform and integrates natively with Site Recovery Manager.

vSphere Replication is configured on a per-VM basis, allowing fine control over which VMs are replicated. This replication can occur from a primary site to a secondary site, between two clusters in a single site, and from multiple source sites to a single target site—regardless of the underlying storage array.

For full details on the architecture, deployment, configuration, and management of vSphere Replication, view the vSphere Replication Technical Overview.

Which features of vSphere work with vSphere Replication?

vSphere Replication is a deeply integrated vSphere component, and it is compatible with many vSphere management features, including the following:

vSphere vMotion
vSphere Storage vMotion
vSphere DRS, vSphere Storage DRS
vSAN Datastore
vSphere Distributed Power Management
vSphere Flash Read Cache

Other vSphere features, such as vSphere Distributed Power Management, require special configuration for use with vSphere Replication. For full compatibility details, view this doc.

Does vSphere Replication maintain a virtual machine's snapshot hierarchy?

No. vSphere Replication does not replicate a virtual machine snapshot hierarchy at the target site. Snapshots are collapsed into a single aggregate virtual machine disk (VMDK) file at the target location. In other words, a virtual machine with snapshots might be configured for replication, but it will be recovered with no snapshots when it is recovered at the target location.

Note: vSphere Replication does include Multiple Point In Time (MPIT) recovery. MPIT recovery enables an administrator to recover a virtual machine to the latest replicated copy at the target site and then roll it back to a previous point in time. When MPIT recovery is configured, these recovery points appear as virtual machine snapshots at the target location when a virtual machine is recovered using vSphere Replication.

What are use cases for vSphere Replication?

Primary use cases for vSphere Replication include:

Data protection locally, within a single site
DR and avoidance between two sites
DR and avoidance to a service provider cloud
Data center migration

More specifically, vSphere Replication is useful for replicating one or more virtual machines:

Within a vSphere cluster or across vSphere clusters at the same site for local data protection, virtual machine migration, and disaster recovery 
Across vSphere clusters at different sites for cross-site data protection, virtual machine migration, and disaster recovery 
From an on-premises data center to a vCloud Hybrid Service provider for disaster recovery 
From one data center to another for use with vCenter Site Recovery Manager

For more questions and answers, check out the full vSphere Replication FAQs.

vSphere Replication