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Speaker(s)

SER2849BU

Sai Inabattini

Extreme Performance Series: Predictive DRS -Performance and Best Practices

VMworld 2017 Content: Not fo

r publication or distri

bution

• This presentation may contain product features that are currently under development.

• This overview of new technology represents no commitment from VMware to deliver these features in any generally available product.

• Features are subject to change, and must not be included in contracts, purchase orders, or sales agreements of any kind.

• Technical feasibility and market demand will affect final delivery.

• Pricing and packaging for any new technologies or features discussed or presented have not been determined.

Disclaimer

#SER2849B CONFIDENTIAL 2



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Case 1

• Some VMs suffer briefly because of periodic resource usage surges in other VMs in my cluster – application performance drop

Case 2

• I tend to reserve capacity for VMs based on their peak load, even when their average loads are much lower – inefficient resource usage

Problem: Occasional Resource Contention




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Addressing Resource Contention

1. Reactive

– Move VMs when the contention happens

– Benefits: Minimal overhead, only move VMs that must be moved

– Performance impact: VMs may suffer briefly, since remediation happens after contention starts

2. Proactive

a) Statically reserve more resources

• Performance impact: No impact, but overprovisioning resources is not good

b) Learn workload pattern, move VMs before resource demand spike

• Performance impact: No impact for regular, periodic workloads

• Cannot handle unexpected short term resource demand spikes

• Cannot predict events that trigger load imbalance




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What Is the Best Solution?

Good balance of both approaches:

Predicting future demands + Reacting to current and future demands

This is predictive-DRS (pDRS)

• New in vSphere 6.5 and vROPs 6.4




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Speaker(s)

SER2849BU

Sai Inabattini

Extreme Performance Series: Predictive DRS -Performance and Best Practices



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Agenda

1 Introduction to pDRS

2 Software requirements and Configuration

3 Application performance case studies

4 Frequently Asked Questions

5 Conclusion




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IntroductionWhat is pDRS?



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What Is Predictive DRS?

• DRS enabled with predictions

• Powerful resource scheduling of DRS + Predictive analytics of vROPs

• Uses both reactive and proactive approaches to balance the workload distribution

vSphere DRS

vRealize Operations

p




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How Does pDRS Work?

Resource usage data

from vCenter

Predictions

Recommendations

DRS/vCenter

vROps




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vROps Dynamic Thresholds (DT)

• Sophisticated Analytics – 10 different algorithms

• Learns Normal Behavior for every metric for every object

• Detects Hourly, daily, monthly patterns

• Generates Upper and Lower bound of “normal” called Dynamic Thresholds (DT)

• This DT is polished and filtered to generate predictions




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Software Requirements and Configuration



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Software Requirements

• vSphere 6.5 (Enterprise+)

• vRealize Operations Manager (vROps) 6.4 and newer

– vROps 6.4: Supports up to 4000 VMs in a cluster

– vROps 6.5 and above, No limits on vROps side

vROps + vSphere 6.5(E+) = pDRS is Free




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Configuration - vSphere

• Enable predictive DRS in the vCenter server

– cluster → configure → vSphere DRS

• Make sure that the clocks in vCenter server and vROps are synced to within a few minutes.

Note: If the clock skew is > 5 Mins, vCenter server discards the predictions




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Configuration – vROps

Enable vCenter adapter to provide stats to pDRS




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Application Performance Case Studies



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Test Scenario

• “Follow the sun” model

Type A – 8 hours

Type B – 8 hours

Type C – 8 hours

Type B starts

Type A ends




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Detecting Workload Surges

• Two cases

– Impact of predictions on the Type A workloads (already running)

– Impact of predictions on the Type B workloads (about to start)

• Test Benchmark: DVDStore

– Benchmark tool that simulates an online store that sells DVDs

– OLTP Database test workload

– Workload is CPU intensive

– Throughput is recorded in transactions per minute

• Test VMs

– Windows VMs

– DVDStore VMs




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• Initial State

Impact on Type A Workloads

DVDStore VMs (Type A)

Idle Windows VMs (Type B)




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Impact on Type A (contd.)

Predictions from vROps for Type B VMs




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• DRS Recommendations (due to predictions for Type B VMs)


pDRS enabled

pDRS disabled




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• Final state after workload surge

With pDRS - Disabled

With pDRS - Enabled




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• Application performance

Type B workload starts

DRS remediates the Imbalance




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Impact on Type B (Newly Started Workloads)

• Initial State

Idle DVDStore VMs (Type B)

Windows VMs (Type A)




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Impact on Type B (contd.)

• Predictions from vROps for Type B VMs




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• DRS Recommendations


pDRS enabled

pDRS disabled




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• Final state after workload surge

pDRS disabled

pDRS enabled




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DVDStore – Effect of load during Application startup

• Application Performance


Application Starts

DRS remediates load imbalance

Workload stabilizes




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II. Distributed Power Management (DPM) with Predictions

• DPM is the cluster level power management engine that provides additional power savings

• Dynamically consolidates workloads during periods of low resource utilization

• Migrates Virtual machines onto fewer hosts and the un-needed ESX hosts are powered off

• When workload demand increases, ESX hosts are powered back




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DPM with Predictions (contd.)




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Distributed Power Management with Predictions (contd.)




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Frequently Asked Questions



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Workloads that pDRS Can Predict

• Any type of workload with periodic usage pattern

• Short spikes in the order of minutes will not be predicted

• More consistent the workload is, more accurate the predictions will be




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Learning Period

• The default learning period is a minimum of 14 days for generating predictions

• Longer the learning period, better the accuracy of predictions

• Predictions will be available only after 14 days of data




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Current Demand vs Future Demand

• pDRS will always ensure current VM demand will not be affected due to future demand

• VM demand = Max(Current demand, Future demand)

• Current demand of VMs will never be clipped in favor of future demand




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Tuning

• Compute Dynamic Thresholds

– You can manually force vROps to collect data for calculating Dynamic Thresholds (DT)

– “Administration” → “Support” → “Dynamic Thresholds”

• Look ahead interval

– Amount of time DRS looks ahead while accounting predictions

– Default value is 1 hour

– Use DRS advanced option ProactiveDrsLookaheadIntervalSecs to change

– Max allowed value is 12 hours




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VMs with Predictions vs VMs without Predictions

• How will pDRS behave when I have a mix of VMs (some with predictions, and some without) in the same cluster?

• VMs with predictions,

– VM demand = Max (Current demand, Future demand)

• VMs without predictions,

– VM demand = Current demand




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Filtering Predictions in the vROPs

• Once a day, vROps sends the next 26 hours of predictions to VC

• For 26 hours, there will be 52 samples, 1 sample for every 30 minutes

• Prediction samples that do not meet the accuracy criteria will be discarded and set to a value -1

• Consecutive identical samples will be merged to send a single multi-hour sample




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• How can I differentiate DRS vMotions due to predictions?

• Resource demand on Host A increased due to increased demand in green and red VMs

• DRS moved blue VMs to Host B to balanced the cluster load

• In this case, DRS chose blue VMs as moving them will balance the cluster faster

Host A

Identify vMotions Due to Predictions

VMs without predictions

VMs with predictions

VMs with predictions dropped

Host B




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Conclusion

• pDRS can help avoid contention before the performance of a VM degrades

• Forecasting in pDRS works best for VMs with periodic workload patterns

• Current demand will never be clipped to favor future demand

• Provides the best solution through Reactive + Predictive approach




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DRS Flings

• DRS Lens

– Provides a simple, yet powerful interface to highlight the value proposition of vSphere DRS

– https://labs.vmware.com/flings/drs-lens

• DRS Dump Insight

– Service portal where users can upload drmdump files and it provides a summary of the DRS run

– https://labs.vmware.com/flings/drs-dump-insight




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https://labs.vmware.com/flings/drs-lens

https://labs.vmware.com/flings/drs-dump-insight

Other Performance Sessions

• vCenter Performance Deep Dive [SER1504BU]

• Extreme Performance Series: Performance Best Practices [SER2724BU]

• Extreme Performance Series: vSAN Performance Troubleshooting [STO1515BU]

• Maximum Performance with Mark Achtemichuk [VIRT2368GU]




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