VMware Virtualization for Java Application Servers

With a growing number of clients and environments we migrated to VMware vSphere 5. Today 80 percent of our non-production environments run on VMs.

Sizing¶

vCPUs: never more than the number of physical cores. RAM: JVM heap + 2–3 GB for the OS. Memory overcommit for Java is NOT RECOMMENDED — the ballooning driver can take memory away from the JVM. Disk: thick provisioned for production.

NUMA awareness¶

Keep the number of vCPUs per VM less than or equal to the cores on a single NUMA node. Otherwise memory access will be slower and GC pauses will be unpredictable.

Java-specific settings¶

Disable ballooning for production Java VMs. Use PVSCSI adapter and VMXNET3 network adapter. Monitor CPU ready time — above 5 percent means insufficient CPU.

HA and vMotion¶

vMotion with no visible impact. vSphere HA automatically restarts VMs. For non-critical applications, VM-level HA is sufficient.

Summary¶

Virtualization works excellently with proper sizing. The savings in cost and flexibility outweigh the 3–5 percent overhead.