What Is Disaster Recovery as a Service (DRaaS)? How It Works and What to Ask

A ransomware attack encrypts your file server on a Monday morning. Or a burst pipe floods the closet that holds your servers. Backups help, but restoring everything onto new hardware can take days. Meanwhile, orders, payroll and customer service stop.

Disaster recovery as a service, usually shortened to DRaaS, exists to shrink that downtime. Instead of rebuilding from scratch, you switch over to copies of your systems that are already running, or ready to run, in a provider’s cloud. This guide explains how DRaaS works, how it differs from backup, what it costs and the questions to ask before you sign up.

What DRaaS means

DRaaS is a cloud service that replicates your servers, virtual machines and data to a provider’s infrastructure and lets you fail over to them during an outage. When your own environment is fixed, you fail back and return to normal operations.

The provider supplies the recovery site, replication software and, depending on the plan, the people who help run the recovery. You avoid building and paying for a second data center that sits idle most of the time.

DRaaS can protect:

• On-premises physical servers and virtual machines.
• Workloads already in one cloud region, replicated to another region.
• Business applications and databases running on those servers.

It is one piece of a wider plan. Federal guidance from Ready.gov advises building an IT disaster recovery plan as part of your business continuity plan, with recovery priorities driven by a business impact analysis. NIST Special Publication 800-34 provides a detailed contingency planning process that many organizations use as a reference.

How DRaaS works, step by step

1. Install an agent or connector. Lightweight software on each protected server, or a connector on your hypervisor, captures changes.
2. Initial sync. A full copy of each server is sent to the provider’s environment.
3. Continuous or scheduled replication. After that, only changes are sent, often every few seconds or minutes, depending on the service.
4. Recovery points. The service keeps snapshots so you can recover to a point before the problem, such as before ransomware encrypted files.
5. Failover. During a disaster, you (or the provider) launch your servers in the recovery environment and redirect users, usually by changing DNS or network routes.
6. Failback. Once your primary site is restored, changed data is synced back and operations move home.
7. Testing. Good services let you launch isolated test copies without affecting production, so you can prove recovery works.

The 2 numbers that define how good your recovery is are your recovery time objective (RTO), how quickly you need a system back, and your recovery point objective (RPO), how much recent data you can afford to lose. Our guide on RTO vs RPO shows how to set targets for each system.

Key takeaway: DRaaS is about keeping the business running, not just keeping copies of files. Its value comes from fast, tested failover. A DRaaS plan you have never tested is a hope, not a recovery plan.

DRaaS vs backup vs high availability

These terms often get mixed up. They solve different problems and many businesses need more than one.

Backup keeps copies of data. DRaaS keeps copies of whole running systems ready to launch. High availability keeps systems up through small failures, but if ransomware or a bad change spreads to every copy, you still need recovery points. Read our guide on how to back up business data for the backup layer; DRaaS builds on top of it, it does not replace it.

Types of DRaaS service

Providers usually offer 3 levels of involvement:

• Self-service DRaaS: You get the tools and the recovery infrastructure; your team configures, tests and runs failover. Cloud provider tools such as AWS Elastic Disaster Recovery and Azure Site Recovery are examples.
• Assisted DRaaS: The provider helps with setup and runbooks and supports you during tests and real events, while you keep some responsibility.
• Managed DRaaS: The provider runs replication, testing and the recovery itself, often under a contract with defined recovery times.

Small teams without dedicated infrastructure staff often lean toward assisted or managed options. Teams with cloud skills may prefer self-service for cost and control.

How DRaaS pricing works

Pricing varies by provider and changes over time, but most plans combine some of these elements:

• Per protected server or VM: A recurring fee for each machine being replicated.
• Replication storage: The disk space for replicas and recovery point snapshots.
• Compute during tests and failover: You pay for running recovered servers only while they run.
• Data transfer: Network charges for moving data, especially out of a cloud region.
• Management fees: For assisted or managed plans, a service fee on top.

Two public examples show the model. AWS lists Elastic Disaster Recovery at a flat hourly rate per source server, covering replication, test launches and recovery launches, with storage, replication servers and recovery instances billed separately. Azure Site Recovery charges per protected instance per month, with each instance free for its first 31 days, plus storage, transactions, egress and compute during failovers. Check each provider’s current pricing page and run their calculator with your own server count, because totals depend heavily on data size and how often you test.

For broader context on cloud bills, see our guide to how cloud pricing works.

Questions to ask before signing up

Use this checklist when comparing providers:

1. What RTO and RPO can you achieve for my systems? Ask for figures based on your data sizes, not marketing maximums.
2. Are those targets in the contract or SLA? What happens if they are missed?
3. How do testing and drills work? Can we test without disrupting production, and how often is testing included?
4. How far back can we recover? How many recovery points are kept and for how long, which matters for ransomware that sits undetected?
5. How is replicated data protected? Ask about encryption in transit and at rest, access controls, immutable copies and isolation from your production credentials.
6. Who declares a disaster and runs failover? What are the support hours and response times?
7. How does failback work, and what does it cost?
8. Where is data stored? Which regions, and does that meet your compliance obligations?
9. What does a real failover cost? Get an estimate for running in the recovery site for a week.
10. What is your responsibility vs ours? DRaaS follows a shared responsibility model; you usually still own application configuration, user access and testing sign-off.

Ask for a sample runbook and, if possible, references from customers of a similar size.

Where to start with DRaaS

1. List your systems and rank them by how much downtime would hurt.
2. Set RTO and RPO targets for each tier. Not everything needs minutes; some systems can wait a day.
3. Check what you already have. Your cloud provider, virtualization platform or backup vendor may already offer DR features.
4. Shortlist 2 or 3 providers and use the questions above.
5. Start with a pilot of 2 or 3 critical servers.
6. Run a full failover test and time it against your RTO.
7. Write the runbook into your incident response plan, including who decides to fail over and how staff and customers are informed.
8. Test on a schedule, at least annually and after major changes.

DRaaS is especially valuable as part of ransomware protection for small business, as long as recovery points go back far enough and the replica environment is isolated from compromised credentials.

Conclusion

DRaaS gives you a ready recovery site without building a second data center. It replicates your systems to a provider’s cloud, lets you fail over in minutes or hours and fail back when the crisis is over. Choose it based on the recovery times your business actually needs, understand the full pricing model, and test it regularly so it works on the day you need it. For more definitions, visit our glossary.

Sources

• Ready.gov: IT Disaster Recovery Plan — building an IT recovery plan tied to business impact analysis, RTO and RPO
• NIST SP 800-34 Rev. 1: Contingency Planning Guide for Federal Information Systems — contingency planning process and business impact analysis template
• AWS Elastic Disaster Recovery pricing — per-source-server hourly pricing and additional charges
• Azure Site Recovery pricing — per-protected-instance pricing, 31-day free period and other charges