"Move everything to the cloud" sounds decisive, but for many businesses it is neither practical nor sensible. Some systems are cheaper, faster or simply easier to run in your own server room or co-located rack. A hybrid cloud combines the two: some workloads run on infrastructure you control, others run with a public cloud provider, and the two are connected so they work as one environment. This article explains how that works and how to decide what goes where.
What hybrid cloud means
The term is used loosely, so it is worth being precise. A hybrid cloud has three ingredients:
- On-premises or private infrastructure: servers in your office, a data centre you lease, or a private cloud platform such as VMware or OpenStack.
- Public cloud services: AWS, Azure, Google Cloud or another provider.
- Connectivity and shared management: secure networking between the two, shared identity (the same user accounts), and ideally common monitoring and deployment tools.
Simply having a website on a cloud server and an unconnected file server in the office is not really hybrid cloud. It becomes hybrid when the two sides are designed to work together.
How the pieces connect
Networking
The most common link is a site-to-site VPN, an encrypted tunnel over the internet between your office firewall and a virtual network gateway in the cloud. It is quick to set up and inexpensive. For higher bandwidth or more predictable latency, providers offer dedicated private connections such as AWS Direct Connect, Azure ExpressRoute and Google Cloud Interconnect, usually provisioned through a telecom or data centre partner.
Plan IP address ranges carefully before connecting anything. If your office uses 192.168.1.0/24 and the cloud network uses the same range, routing will not work. Choose a distinct block for the cloud, such as 10.20.0.0/16.
Identity
Users should sign in once and reach resources on both sides. Many organisations synchronise on-premises Active Directory with Microsoft Entra ID, or use a single identity provider for both environments. Separate sets of passwords for "cloud" and "office" quickly become a security problem.
Management
Tools such as Azure Arc, Google Distributed Cloud and AWS Outposts or Systems Manager extend cloud management to on-premises servers. Open-source options like Ansible, Terraform and Prometheus work across both environments too, and avoid tying your operations to one vendor.
When to keep workloads on-premises
These are the situations where keeping a system local is often the better choice:
- Steady, predictable, heavy load. A server that runs flat out around the clock, year after year, gains little from cloud elasticity. Owned hardware, fully depreciated, can be cheaper over its life.
- Low latency to local equipment. Factory machines, point-of-sale systems, medical devices and CCTV recorders often need a server on the same site, and must keep working if the internet link drops.
- Large local data sets. Video editing, CAD files or scanning workflows move huge files. Shuttling them over the internet is slow, and egress fees apply when pulling data back out of the cloud.
- Regulatory or contractual constraints. Some contracts or sector rules require data to stay in a specific location or on infrastructure you control.
- Legacy systems. Software tied to old operating systems, dongles or specific hardware may be impossible or uneconomic to move until it is replaced.
- Recently purchased hardware. Moving off servers you bought last year wastes money; plan the move for their end of life.
When the cloud side wins
- Variable or seasonal demand, such as an online shop at festival time, where you can scale up for weeks and back down.
- Customer-facing websites and APIs that benefit from good internet connectivity, CDNs and multiple availability zones.
- New projects and experiments, where buying hardware upfront is a risk.
- Offsite backups and disaster recovery, a classic hybrid use case: production on-premises, copies and standby capacity in the cloud.
- Managed services such as databases, email or analytics, where the provider's operational work replaces yours.
Common hybrid patterns
| Pattern | On-premises | Cloud |
|---|---|---|
| Cloud backup and DR | Production servers | Backup copies, standby VMs |
| Cloud front end | ERP and core database | Website, customer portal, APIs |
| Cloud bursting | Normal capacity | Extra capacity during peaks |
| Edge plus cloud | Local processing at branches or factories | Central reporting and storage |
"Cloud bursting" is often discussed but harder than it sounds, because applications and data must be ready to run in both places at short notice. For most small and mid-sized businesses, backup and DR or a cloud-hosted front end are more realistic starting points.
Challenges to plan for
- Two environments to secure. Patch, monitor and audit both. A VPN connects networks, which means a breach on one side can reach the other unless you restrict traffic with firewall rules.
- Skills. Your team needs to understand both traditional infrastructure and cloud services.
- Data consistency. Systems split across sites need clear rules about which copy is authoritative.
- Visibility. Use one monitoring dashboard for both sides, or problems will hide in the gaps.
When a hybrid design is right for you, the work is mostly in the planning: address ranges, identity, security boundaries and backup flows. Our cloud solutions and server management services cover both sides of that boundary.
Key takeaways
- Hybrid cloud means on-premises and cloud resources deliberately connected and managed together.
- Keep workloads local when load is steady, latency to local equipment matters, data is huge, or rules require it.
- Use the cloud for variable demand, public-facing services, new projects and offsite backup.
- Plan IP ranges, shared identity, security boundaries and monitoring before connecting the two.