# Maximising VM Density: Getting More From Your Virtualisation Platform
Virtualisation transformed data centre economics. Instead of one application per physical server, dozens of virtual machines share hardware. Resource utilisation increased dramatically. Capital efficiency improved.
But virtualisation potential often goes unrealised. Conservative sizing leaves capacity unused. Poor placement creates hotspots. Memory overcommit hesitancy wastes RAM. Maximising VM density extracts full value from infrastructure investment.
## Understanding Density Drivers
Several factors affect achievable density.
**CPU overcommit** shares processor resources. Virtual CPUs exceed physical cores. Scheduling distributes load. Works well when VMs are not CPU-intensive simultaneously.
**Memory management** enables consolidation. Transparent page sharing deduplicates common pages. Ballooning reclaims unused memory. Compression and swap provide overflow handling.
**Storage I/O** often constrains density. Many VMs contending for storage bandwidth create latency. Flash storage alleviates but does not eliminate contention.
**Network bandwidth** typically headroom exists. Modern 10Gb and faster NICs provide ample capacity. Traffic shaping prevents VM interference.
## Optimisation Techniques
Several approaches improve density.
**Right-sizing** eliminates waste. VMs provisioned for peak rarely use full allocation. Monitoring reveals actual usage. Resize to actual requirements.
**Workload placement** distributes load intelligently. DRS and equivalent features balance across hosts. Anti-affinity rules separate competing workloads. Placement policies encode operational knowledge.
**Resource pools** manage allocation. Guarantees ensure critical VMs get resources. Limits prevent runaway consumption. Shares determine relative priority.
**Templates and standards** prevent sprawl. Standard VM sizes simplify management. Templates enforce consistency. Limits on maximum sizes prevent waste.
## Monitoring and Adjustment
Density optimisation is ongoing.
**Performance monitoring** identifies constraints. Which resource limits density? CPU ready time indicates CPU contention. Memory ballooning suggests memory pressure.
**Capacity planning** projects future needs. Growth trends inform infrastructure planning. Avoid both over-provisioning waste and under-provisioning crisis.
**Regular review** catches drift. Initial right-sizing degrades as workloads change. Periodic assessment maintains optimisation.
If your organisation needs help optimising virtualisation infrastructure or improving data centre efficiency, contact us through our contact page.
## Density Without Regret
VM density is not a badge of honour if performance collapses. Watch:
- CPU ready time / steal time,
- storage latency,
- and memory contention.
## Practical Optimisation Steps
- standardise VM sizing (avoid thousands of unique shapes),
- remove abandoned VMs,
- and tune overcommit ratios based on measured behaviour.
The best density improvements usually come from cleaning up sprawl and rightsizing.