VMworld 2012: vSphere Performance Best Practices INF-VSP1800

Speaker: Pete Boone

This session covered various aspects of a virtualized infrastructure that need to be looked at when optimizing performance. The basic four food groups are memory, CPU, network, and storage.

• Benchmarking and Tools
• Consistent and reproducible results
• Important to have a baseline of acceptable performance
• Determine baseline of performance prior to deployment
• Avoid subjective metrics, stay quantitative
• Benchmarking should be done at the application layer
• Use application-specific benchmarking tools and load generators
• Isolate variables, benchmark optimum situation before introducing load
• Understand dependencies (human interaction, compare apples-to-apples)
• Tools - vCenter Operations, ESXtop
• Memory
• vRAM + overhead = maximum physical memory
• Transparent page sharing
• Ballooning
• Compression
• Swapping
• Right sizing - Better to over-commit than under-commit
• Don't use memory limits!
• Ballooning is a warning sign, but not a problem
• Swapping is a problem if over an extended period
• Swapping/paging at the guest level - Under-provisioned guest memory
• Missing balloon driver (VMware Tools)
• Best practices
• Avoid high active host memory over-commitment
• Right-size guest memory
• Ensure there is enough vRAM to cover demand peaks
• Use fully automated DRS cluster
• Use resource pools with high/normal/low shares
• Avoid custom shares setting
• CPU
• CPU cores/threads have to be shared among all VMs
• ESXtop
• %USED - Physical CPU usage
• %SYS - Percentage of time in the VMkernel
• %RUN - Percentage of total scheduled time
• %WAIT
• %IDLE - %WAIT - %IDLE can be used to estimate IO wait time
• vCPUs
• Relaxed co-scheduling in vSphere 4.x and higher
• Idle vCPUs incur a scheduling penalty
• Configure only as many vCPUs as needed
• Use uniprocessor VMs for single-threaded applications
• CPU Ready Time
• Does not necessairly indicate a problem
• vCPU to pCPU allocation - Hyper-threading adds about 30% performance
• Don't set too may limits or reservations
• Right sizing vSMP VMs
• Storage
• ESXTOP views - Adapter (d), VM (v), Disk device (U)
• High DAVG - Issue beyond the adapter
• High KAVG - Issue is in the kernel storage stack - Driver issue, queue
• Use Storage DRS
• Snapshots - causes extra load to locate blocks
• Excessive traffic down one HBA/switch/storage processor can cause latency
• Use paravirtual SCSI adapater
• Networking
• Load balancing on Port ID is the most compatible
• Check counters for NICs and VMs
• 10Gbps NICs can incur significant CPU load when running at 100%
• If using jumbo frames, ensure it is enabled end to end
• Use VMXNET3 adapter