In my day job I am often asked about the use of cloud for disaster recovery. Some organisations only operate out of a single data centre, or building, while others have a dual-site setup but want to explore a third option in the cloud. Either way, using cloud resources for disaster recovery can be a good way to learn and validate different technologies, potentially with a view to further migrations as data centre and hardware contracts expire.
This post takes a look at the different cloud-based disaster recovery options available for VMware workloads. It is not an exhaustive list but provides some ideas. Further work will be needed to build a resilient network architecture depending on the event you are looking to protect against. For example do you have available network links if your primary data centre is down, can your users and applications still route to private networks in the cloud, are your services internet facing allowing you to make your cloud site the ingress and egress point. As with any cloud resources, in particular if you are building your own services, a shared security model applies which should be fully understood before deployment. Protecting VMware workloads should only form part of your disaster recovery strategy, other dependencies both technical and process will also play a part. For more information on considering the bigger picture see Disaster Recovery Strategy – The Backup Bible Review.
- DRaaS (Disaster Recovery as a Service) – A managed service that will typically involve some kind of data replication to a site where the infrastructure is entirely managed by the service provider. The disaster recovery process is built using automated workflows and runbooks; such as scaling out capacity, and bringing online virtual machines. An example DRaaS is VMware Cloud Disaster Recovery which we’ll look at in more detail later on.
- SaaS (Software as a Service) – An overlay software solution may be able to manage the protection of data and failover, but may not include the underlying infrastructure components as a whole package. Typically the provider manages the hosting, deployment, and lifecycle management of the software, but either the customer or another service provider is responsible for the management and infrastructure of the protected and recovery sites.
- IaaS and PaaS (Infrastructure as a Service and Platform as a Service) – Various options exist around building disaster recovery solutions based on infrastructure or platforms consumed from a service provider. This approach will generally require more effort from administrators to setup and manage but may offer greater control. An example is installing VMware Site Recovery Manager (self-managed) to protect virtual machines running on VMware-based IaaS. Alternatively third party backup solutions could be used with cloud storage repositories and cloud hosted recovery targets.
- Hybrid Cloud – The VMware Software Defined Data Centre (SDDC) can run on-premises and overlay cloud providers and hyperscalers, delivering a consistent operating platform. Disaster recovery is one of the common use cases for a hybrid cloud model, as shown in the whiteboard below. Each of the solutions covered in this post is focused around a hybrid cloud deployment of VMware software in an on-premises data centre and in the cloud.
VMware Cloud Disaster Recovery
VMware Cloud Disaster Recovery (VCDR) replicates virtual machines from on-premises to cloud based scale-out file storage, which can be mounted to on-demand compute instances when required. This simplifies failover to the cloud and lowers the cost of disaster recovery. VCDR allows for live mounting of a chosen restore point for fast recovery from ransomware. Recently ransomware has overtaken events like power outages, natural disasters, human error, and hardware failure as the number one cause of disaster recovery events.
VCDR uses encrypted AWS S3 storage with AWS Key Management Service (KMS) as a replication target, protecting virtual machines on-premises running on VMware vSphere. There is no requirement to run the full SDDC / VMware Cloud Foundation (VCF), vSAN, or NSX at the replication source site. If and when required, the scale-out file system is mounted to compute nodes using VMware Cloud (VMC) on AWS, without the need to refactor or change any of the virtual machine file formats. VCDR also includes built-in audit reporting, continuous healthchecks at 30 minute intervals, and test failover capabilities.
VMware Cloud on AWS provides the VMware SDDC as a managed service running on dedicated AWS bare-metal hardware. VMware manage the full infrastructure stack and lifecycle management of the SDDC. The customer sets security and access configuration, including data location. Currently VCDR is only available using VMware Cloud on AWS as the target for cloud compute, with the following deployment options:
- On Demand – virtual machines are replicated to the scale-out file storage, when disaster recovery is invoked an automated SDDC deployment is initiated. When the SDDC is ready the file system is mounted to the SDDC and virtual machines are powered on. Typically this means a Recovery Time Objective (RTO) of around 4 hours. For services that can tolerate a longer RTO the benefit of this deployment model is that the customer only pays for the storage used in the scale-out storage, and then pays for the compute on-demand should it ever be needed.
- Pilot Light – a small VMware Cloud on AWS environment exists, typically 3 hosts. Virtual machines are replicated to the scale-out file storage, when disaster recovery is invoked the file system is instantly mounted to the existing SDDC and virtual machines are powered on. Depending on the number of virtual machines being brought online, the SDDC automatically scales out the number of physical nodes. This brings the RTO time down to as little as a few minutes. The customer is paying for the minimum VMware Cloud on AWS capacity to be already available but this can be scaled out on-demand, offering significant cost savings on having an entire secondary infrastructure stack.
The cloud-based orchestrator behind the service is provided as SaaS, with a connector appliance deployed on-premises to manage and encrypt replication traffic. After breaking replication and mounting the scale-out file system administrators manage virtual machines using the consistent experience of vSphere and vCenter. Startup priorities can be set to ensure critical virtual machines are started up first. At this point virtual machines are still running in the scale-out file system, and will begin to storage vMotion over to the vSAN datastore provided by the VMware Cloud on AWS compute nodes. The storage vMotion time can vary depending on the amount of data and number of nodes (more nodes and therefore physical NICs provides more network bandwidth), however the vSAN cache capabilities can help elevate any performance hit during this time. When the on-premises site is available again replication reverses, only sending changed blocks, ready for failback.
You can try out VCDR using the VMware Cloud Disaster Recovery Hands-On Lab, additional information can be found at the VMware Cloud Disaster Recovery Solution and VMware Cloud Disaster Recovery Documentation pages.
VMware Site Recovery Manager
VMware Site Recovery Manager (SRM) has been VMware’s main disaster recovery solution for a number of years. SRM enables policy-driven automation of virtual machine failover between sites. Traditionally SRM has been used to protect vSphere workloads in a primary data centre using a secondary data centre also running a VMware vSphere infrastructure. One of the benefits of the hybrid cloud model utilising VMware software in a cloud provider like AWS, Azure, Google Cloud, or Oracle Cloud, is the consistent experience of the SDDC stack; allowing continuity of solutions like SRM.
SRM in this scenario can be used with an on-premises data centre as the protected site, and a VMware stack using VMware Cloud on AWS, Azure VMware Solution (AVS), Google Cloud VMware Engine (GCVE), or Oracle Cloud VMware Solution (OCVS) as the recovery site. SRM can also be used to protect virtual machines within one of the VMware cloud-based offerings, for example failover between regions, or even between cloud providers. Of these different options Site Recovery Manager can be deployed and managed by the customer, whereas VMware Cloud on AWS also offers a SaaS version of Site Recovery Manager; VMware Site Recovery, which is covered in the next section.
SRM does require the recovery site to be up and running but can still prove value for money. Using the hybrid cloud model infrastructure in the cloud can be scaled out on-demand to fulfil failover capacity, reducing the amount of standby hardware required. The difference here is that vSphere Replication is replicating virtual machines to the SDDC vSAN datastore, whereas VCDR replicates to a separate scale-out file system. The minimum number of nodes may be driven by storage requirements depending on the amount of data being protected. The recovery site could also be configured active/active, or run test and dev workloads that can be shut down to reclaim compute capacity. Again storage overhead is a consideration when deploying this type of model. Each solution will have its place depending on the use case.
SRM allows for centralised recovery plans of VMs and groups of VMs, with features like priority groups, dependencies, shut down and start up customisations, including IP address changes using VMware Tools, and non-disruptive recovery testing. If you’ve used SRM before the concept is the same for using a VMware cloud-based recovery site as a normal data centre; an SRM appliance is deployed and registered with vCenter to collect objects like datastores, networks, resource pools, etc. required for failover. If you haven’t used SRM before you can try it for free using either the VMware Site Recovery Manager Evaluation, or VMware Site Recovery Hands-on Lab. Additional information can be found at the VMware Site Recovery Manager Solution and VMware Site Recovery Manager Documentation pages.
VMware Site Recovery
VMware Site Recovery is the same product as Site Recovery Manager, described above, but in SaaS form. VMware Site Recovery is a VMware Cloud based add-on for VMware Cloud on AWS. The service can link to Site Recovery Manager on-premises to enable failover to a VMware Cloud on AWS SDDC, or it can provide protection and failover between SDDC environments in different VMware Cloud on AWS regions. At the time of writing VMware Site Recovery is not available with any other cloud providers. As a SaaS solution VMware Site Recovery is naturally easy to enable, it just needs activating in the VMware Cloud portal. You can find out more from the VMware Site Recovery Solution page.
For more information on the solutions listed see the VMware Disaster Recovery Solutions page, and check in with your VMware account team to understand the local service provider options relevant to you. There are other solutions available from VMware partners and backup providers. Your existing backup solution for example may offer a DRaaS add-on, or the capability to backup or replicate to cloud storage which can be used to build out your own disaster recovery solution in the cloud.
The table below shows a high level comparison of the difference between VMware Cloud Disaster Recovery and Site Recovery Manager offerings. As you can see there is a trade off between cost and speed of recovery, there are use cases for each solution and in some cases maybe both side by side. Hopefully in future these products will fully integrate to allow DRaaS management from a single interface or source of truth where multiple Recovery Point Objective (RPO) and RTO requirements exist.
|VMware Cloud Disaster Recovery||On demand DRaaS||Cloud based file system||Live mount when capacity is available||~4 hours||Per VM, per TiB of storage, list price is public here. VMC on AWS capacity may be needed*|
|VMware Site Recovery||Hot DRaaS||Directly to failover capacity||Fast RTOs using pre-provisioned failover capacity||As low as 5 minutes with vSAN at the protected site, or 15 minutes without vSAN||Per VM, list price is public here. vSphere Replication is also needed**|
|VMware Site Recovery Manager||Self-managed||Directly to failover capacity||Fast RTOs using pre-provisioned failover capacity||As low as 5 minutes with vSAN at the protected site, or 15 minutes without vSAN||Per VM, in packs of 25 VMs. vSphere Replication is also needed**|
*VMware Cloud on AWS capacity is needed depending on the deployment model, detailed above. For pilot light a minimum of 3 nodes are running all the time, these can be discounted using 1 or 3 year reserved instances. For on-demand if failover is required then the VMC capacity is provisioned using on-demand pricing. List price for both can be found here, but VMware also have a specialist team that will work out the sizing for you.
**vSphere Replication is not sold separately but is included in the following versions of vSphere: Essentials Plus, Standard, Enterprise, Enterprise Plus, and Desktop.