Among the many challenges an organization and its IT department confront on a daily basis, availability of services is particularly critical for the survival of the businesses that entrust and rely on the technologies on which their services have been built. At the same time, several legislations across different countries are creating continuous pressure on each and every organization to maintain an appropriate plan to protect and secure their data and their services.
Historically, every large enterprise has planned and built its own approach to face a disaster of small or large proportions in the most suitable way for their businesses: backups, hardware redundancy, host clustering, data mirroring, replication, geographically distributed sites, and so on, are just few identifiers for technologies and strategies to build a solution trying to address the problem.
Over the years, some of these technologies have been commoditized. Still for some of them, the financial burden to allow their implementation has been an overwhelming capital expense for many medium and small organizations. In addition, expertise is required to manage and organize the software, hardware, and storage components involved.
In this context, a great opportunity for cloud service providers has materialized. The market has increased its confidence in using cloud-based services offering a more cost-effective (subscription based) access to resources. Disaster recovery as a service (DRaaS) is a highly desirable service to offer to all organizations, but particularly for the ones that might have concerns or financial exposures caused by planning and building their own secondary data center site to make their services more robust and resilient to local disasters.
This blog post highlights the benefits for VMware vCloud® Air™ Network providers in leveraging the recently announced VMware vCloud Availability for vCloud Director® solution to establish a DRaaS offering for their tenants. A complete reference architecture example is currently being built and will be released during the current quarter as part of the VMware vCloud Architecture Toolkit™ for Service Providers.
vCloud Availability for vCloud Director introduction
The solution is purposely designed for vCloud Air Network service providers and plugs seamlessly into a pre-existing vCloud Director multitenant environment. The value proposition for the solution is that it is:
- Easy to operate for service providers. It is compatible with the VMware vSphere® environments on the tenants’ end
- Easy to adopt and use for tenants. Involves use of native VMware vSphere Replication™ with a plug-in user interface
- Designed for vCloud Air Network service providers with native vCloud Director integration. Offers multitenant and self-service capabilities.
The key system requirements for the solutions on the service provider side are as follows:
- VMware vCloud Director 8.10
- VMware vCenter Server® / VMware ESXi™ 6.0 U2
- VMware NSX® version certified for vCloud Director
- RabbitMQ 3.4.3
- Cassandra 2.2
- vCloud Availability for vCloud Director 1.0
The requirements in the tenant on-premises environment include the following:
- vCenter Server 5.1, 5.5 U2, 6.0 U1 (with different levels of compatibility)
- ESXi host 5.0, 5.1.x, 5.5.x, and 6.0
- vSphere Replication appliance
- Internet connectivity between the on-premises data center and the vCloud Air Network service provider
Use case for vCloud Availability
This use case is a hybrid scenario where a customer with a vSphere on-premises environment wants to protect workloads by taking advantage of a service provider as a secondary site, typically targeting the tier 1 to 2-4 applications, where the different tiers are defined in the following table.
|Service Level||Tier||Use Case||RPO (Recovery Point Objective)|
|Premium||0-1||High Availability or Mission Critical DR||No data loss, Seconds|
|Standard||1-2||Mission Critical DR||Minutes|
|Basic||2-4||Business Critical DR or Backup||15 min / 24h, backup|
vCloud Availability for vCloud Director offers DR services by asynchronously replicating the workloads (VMs) to the service provider site, which is running vCloud Director. From the service provider standpoint, each tenant has their own DR instance with the appropriate resources as defined by their service plan.
The solution provides a warm stand-by environment with self-service protection because the tenant can independently select the workloads (VMs) to protect. This solution operates with an RPO between 15 minutes to 24 hours as chosen by the tenant, and a RTO (Recovery Time Objective) that is dependent on the time required to power on the VMs.
vCloud Availability for vCloud Director offers a set of different capabilities depending on the versions of the components available on the tenant site. The more recent the version of vCenter Server / ESXi, the more advanced options are available to the tenant to operate a recovery from a failure.
Failover from on-premises to vCloud Air Network service provider – after the VMs have been replicated to the secondary site in the service provider cloud environment, a failover can occur and the workloads will be executed from the service provider data centers.
Failback to tenant on-premises – after the execution of the workloads has been migrated to the cloud in the service provider data centers, workloads can then failback to the tenant on-premises environment.
Multiple Point in Time (MTIP) – up to 24 restore points can be created and restoration is available from any of these recovery points, offering a greater failover control.
|Feature Compatibility||vCenter Server 6.0U1||vCenter Server 5.5 U2||vCenter Server 5.1|
|Supported ESXi versions||6.0, 5.5, 5.1, 5.0||5.5, 5.1, 5.0||5.1, 5.0|
|Supported vSphere Replication versions||6.1.x, 6.0.x||5.8.x, 5.6.x||5.8.x, 5.6.x|
|Failback||Supported||Not supported||Not supported|
|Multiple Point in Time (MPIT)||Supported||Not supported||Not supported|
The amount of storage required for the service provider site depends on a multiplier of the base size of a VM (base size, plus the size for the current replica, plus the size for all the MPIT instances maintained, which can be significant depending on the change rate of the source VM).
vCloud Availability for vCloud Director logical architecture
vCloud Availability for vCloud Director uses vSphere Replication technology, which is natively embedded in the ESXi hypervisor and is storage independent, easily enabling a hybrid, cross-cloud replication scenario.
On the tenant side, a single VM is deployed and provides management services for the replication activities from the entire tenant vSphere environment. The standard replication is in charge of transporting the data to the service provider target environment.
On the service provider side, multiple components cooperate to support inbound (or outbound) replication, secure communications, and store transferred data. Each component can scale horizontally to handle an increased load for each tenant, and for multiple tenants.
The main components at work during replication are the following:
- vSphere Replication appliance –on-premises vSphere Replication component that combines both manager and replication functionality
- vSphere Replication Cloud Service (vRCS) – a tenant-aware replication manager providing the required REST-API to manage the service and all the components
- vSphere Replication Manager (vRMS) – manages the replication process end-to-end from the tenant to the service provider. One vSphere Replication Manager runs for each vCenter Server
- vSphere Replication Server (vRS) – sends or receives the replication data and records the changes for each replicated VM
- vCloud Director (and its cells) – multi-tenant solution for service provider
- Cloud proxy –provides the end point for the tunnels used to replicate data to/from the on-premises environment. Multiple instances are supported and can be load balanced
- Cassandra – open source distributed database to store metadata inherent in the replication, as well as the replicated VMs and configurations
- RabbitMQ: open source message broker implementing Advanced Message Queuing Protocol (AMQP) within the components
VMware vCloud Availability for vCloud Director provides a simple, easy to use solution that is integrated with pre-existing vCloud Air Network service provider components, offering a Disaster recovery as a service platform that can be quickly implemented to take advantage of a growing market.
For more details on this or other vCloud Air Network solutions, visit the VMware vCloud Architecture Toolkit site.