Short answer: Broadcom does not publish a fixed maximum number of VCF instances per VCF fleet in VCF 9.0. A fleet is defined by one VCF Operations and one VCF Automation deployment, so the practical limit is how many objects and metrics that VCF Operations cluster can collect. The largest supported cluster, 12 Extra Large nodes, handles about 1,056,000 objects and 126 million metrics. Network latency and your availability requirements set the other limits.
VCF fleet vs VCF instance in VCF 9.0
VCF 9.0 adds a level above the instance. The hierarchy is VCF private cloud, then fleet, then instance, then domain, then cluster. The VCF fleet deployment models page in the design guide splits the components like this:
| Scope | Components |
|---|---|
| Per VCF fleet (one set) | VCF Operations (monitoring, logs, licensing, fleet lifecycle, certificates, passwords, identity), VCF Automation |
| Per VCF instance | Management domain with SDDC Manager, vCenter and NSX Manager, optional VI workload domains, the instance’s vSphere clusters, storage and networking |
The VCF Installer either starts a new fleet, where the first instance also hosts the fleet management components, or adds a new VCF instance to an existing fleet. A fleet can also include standalone vCenter instances that VCF Operations manages.
Why there is no single “instances per fleet” maximum
Each instance is self-contained: its own SDDC Manager, vCenters and NSX. What all instances in a fleet share is the fleet layer. VCF Operations does not size itself by instances or hosts. It sizes by the number of objects (VMs, hosts, datastores, NSX objects and so on) and metrics it collects. Ten small instances and two very large ones can therefore put the same load on the fleet. That is why the limit is expressed in objects and metrics rather than as an instance count.
VCF Operations 9.0 sizing that bounds a fleet
Values from Broadcom KB 397782 – VCF Operations 9.0 Sizing Guidelines (standard, non-extended cluster):
| Node size | vCPU / RAM | Max nodes | Max objects (cluster) | Max metrics (cluster) |
|---|---|---|---|---|
| Extra Small | 2 / 8 GB | 1 | 700 | 140,000 |
| Small | 4 / 16 GB | 2 | 12,000 | 2,800,000 |
| Medium | 8 / 32 GB | 8 | 136,000 | 32,000,000 |
| Large | 16 / 48 GB | 16 | 576,000 | 81,600,000 |
| Extra Large | 24 / 128 GB | 12 | 1,056,000 | 126,000,000 |
Notes from the same KB:
- All nodes in a multi-node cluster must be the same size.
- Per-node object capacity in a multi-node cluster is lower than for a single node. For Extra Large it is 88,000 per node, compared with 100,000 for a single node.
- An adapter instance (for example a large vCenter) that exceeds a node collector’s capacity can be pinned to a Cloud Proxy. Each node supports up to 200 Cloud Proxies on Large and Extra Large configurations.
- Latency limits apply between analytics nodes and between nodes and Cloud Proxies. A fleet spread across distant regions has to stay within them.
How to plan the number of instances in a fleet
- Estimate objects and metrics per instance: hosts, VMs, datastores and NSX objects, plus any management packs you enable. Broadcom’s sizing worksheet referenced in the KB does this.
- Add up all planned instances and standalone vCenters and pick a VCF Operations size with headroom for growth.
- Check the latency and bandwidth from every site to the VCF Operations nodes and Cloud Proxies.
- Decide on fault domains. Because one fleet means one VCF Operations and one VCF Automation, compliance, tenancy or DR boundaries can be reasons to run several smaller fleets instead of one large one.
For a lab, one fleet with one instance is enough. See deploying a minimal VCF 9.0 lab. For licensing and edition differences, see the vSphere 9.0 product line comparison.
Further reading
- William Lam: How many VMware Cloud Foundation (VCF) Instances can a VCF Fleet support? (original post)
- Broadcom KB 397782: VCF Operations 9.0 Sizing Guidelines
- Broadcom TechDocs: VMware Cloud Foundation Fleet Deployment Models
