Tag Archives: esxtop

VCAP-DCA Study guide – 6.4 Troubleshooting Storage Performance and Connectivity

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Knowledge

  • Recall vicfg-* commands related to listing storage configuration
  • Recall vSphere 4 storage maximums
  • Identify logs used to troubleshoot storage issues
  • Describe the VMFS file system

Skills and Abilities

  • Use vicfg-* and esxcli to troubleshoot multipathing and PSA?related issues
  • Use vicfg-module to troubleshoot VMkernel storage module configurations
  • Use vicfg-* and esxcli to troubleshoot iSCSI related issues
  • Troubleshoot NFS mounting and permission issues
  • Use esxtop/resxtop and vscsiStats to identify storage performance issues
  • Configure and troubleshoot VMFS datastores using vmkfstools
  • Troubleshoot snapshot and resignaturing issues

Tools

There’s obviously a large overlap between diagnosing performance issues and tuning storage performance, so check section 3.1 in tandem with this objective.

Recall vicfg-* commands related to listing storage configuration

  • vicfg-scsidevs
  • vmkiscsi-tool
  • vicfg-mpath
  • vicfg-iscsi
  • esxcli corestorage | nmp | swiscsi
  • vicfg-nas
  • showmount -e
  • esxtop/resxtop
    • look for CONS/s – this indicates SCSI reservation conflicts and might indicate too many VMs in a LUN. This field isn’t displayed by default (press ‘f’ then ‘f’ again to add it)
  • vscsiStats
  • vmkfstools
  • vicfg-module

Continue reading VCAP-DCA Study guide – 6.4 Troubleshooting Storage Performance and Connectivity →

VCAP-DCA Study notes 6.2 – Troubleshoot CPU and Memory Performance

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Knowledge

  • Identify resxtop/esxtop metrics related to memory and CPU
  • Identify vCenter Server Performance Chart metrics related to memory and CPU

Skills and Abilities

  • Troubleshoot ESX/ESXi Host and Virtual Machine CPU performance issues using appropriate metrics
  • Troubleshoot ESX/ESXi Host and Virtual Machine memory performance issues using appropriate metrics
  • Use Hot?Add functionality to resolve identified Virtual Machine CPU and memory performance issues

Tools & learning resources

This is another objective that’s hard to quantify – experience will be the main requirement! There are some great general purpose resources out there;

Note that resxtop (built in to the vMA) does not offer the ‘replay’ mode available in ESX classic. Source: VMworld session MA6580, vMA Tips and Tricks. Continue reading VCAP-DCA Study notes 6.2 – Troubleshoot CPU and Memory Performance →

VCAP-DCA Study notes – 3.5 Utilize Advanced vSphere Performance Monitoring Tools

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This is one objective where you definitely have to get hands on – there’s no way you’ll learn esxtop otherwise. Ideally you’ll have a real infrastructure to play with as you want hosts with memory contention, ballooning, swapping, NUMA optimisations etc so you can play with and understand the features.

Knowledge

  • Identify hot keys and fields used with resxtop/esxtop
  • Identify fields used with vscsiStats

Skills and Abilities

  • Configure esxtop/resxtop custom profiles
  • Determine use cases for and apply esxtop/resxtop Interactive, Batch and Replay modes
  • Use vscsiStats to gather storage performance data
  • Use esxtop/resxtop to collect performance data
  • Given esxtop/resxtop output, identify relative performance data for capacity planning purposes

Tools & learning resources

Using resxtop

Two ways of invoking;

  • resxtop –server <esxi host>
  • resxtop –server <vCenter server> –vihost <esxi host>

Continue reading VCAP-DCA Study notes – 3.5 Utilize Advanced vSphere Performance Monitoring Tools →

VCAP-DCA Study notes – 3.1 Tune and Optimize vSphere Performance

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It’s hard to know what to cover in this objective as performance tuning often implies troubleshooting (note the recommended reading of Performance Troubleshooting!) hence there’s a significant overlap with the troubleshooting section. Luckily there are plenty of excellent resources in the blogosphere and from VMware so it’s just a case of reading and practicing.

Knowledge

  • Identify appropriate BIOS and firmware setting requirements for optimal ESX/ESXi Host performance
  • Identify appropriate ESX driver revisions required for optimal ESX/ESXi Host performance
  • Recall where to locate information resources to verify compliance with VMware and third party vendor best practices

Skills and Abilities

  • Tune ESX/ESXi Host and Virtual Machine memory configurations
  • Tune ESX/ESXi Host and Virtual Machine networking configurations
  • Tune ESX/ESXi Host and Virtual Machine CPU configurations
  • Tune ESX/ESXi Host and Virtual Machine storage configurations
  • Configure and apply advanced ESX/ESXi Host attributes
  • Configure and apply advanced Virtual Machine attributes
  • Tune and optimize NUMA controls

Tools & learning resources

Identify BIOS and firmware settings for optimal performance

This will vary for each vendor but typical things to check;

  • Power saving for the CPU.
  • Hyperthreading – should be enabled
  • Hardware virtualisation (Intel VT, EPT etc) – required for EVC, Fault Tolerance etc
    NOTE: You should also enable the ‘No Execute’ memory protection bit.
  • NUMA settings (node interleaving for DL385 for instance. Normally disabled – check Frank Denneman’s post.
  • WOL for NIC cards (used with DPM)

Identify appropriate ESX driver revisions required for optimal host performance

I guess they mean the HCL. Let’s hope you don’t need an encyclopaedic knowledge of driver version histories!

Tune ESX/i host and VM memory configurations

Read this great series of blog posts from Arnim Van Lieshout on memory management – part one, two and three. And as always the Frank Denneman post.

Check your Service Console memory usage using esxtop.

Hardware assisted memory virtualisation

Check this is enabled (per VM). Edit Settings -> Options -> CPU/MMU Virtualisation;

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Enabling h/w CPU/memory assist for a VM

NOTE: VMware strongly recommend you use large pages in conjunction with hardware assisted memory virtualisation. See section 3.2 for details on enabling large memory pages. However enabling large memory pages will negate the efficiency of TPS so you gain performance at the cost of higher memory usage. Pick your poison…(and read this interesting thread on the VMware forums)

Continue reading VCAP-DCA Study notes – 3.1 Tune and Optimize vSphere Performance →