Vmwareperformancetroubleshooting 100224104321-phpapp02
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This document provides an overview of VMware performance troubleshooting. It covers topics like root cause analysis, monitoring tools like ESXTOP and vm-support, and how to optimize various resources like CPU, memory, networking, and disk. Design best practices are also discussed, such as standard configurations, capacity planning cautions, and concluding with reference articles. The goal is to help troubleshoot and resolve virtualization performance issues.
Vmwareperformancetroubleshooting 100224104321-phpapp02
- 1. VMware Performance Troubleshooting Presented by Chris Kranz
- 2. Topics Covered • Introduction • Root Cause Analysis • Performance Characteristics • CPU • Networking • Memory • Disk • Virtual Machine optimisation • ESXTop • vm-support • Service Console • Resource Groups • Design Guidelines • Capacity Planner limitations and cautions • Conclusion • Reference Articles
- 3. Introduction Multiple layers of virtualisation are used to increase service levels, availability and manageability However, multiple layers of virtualisation often mask performance and configuration issues making it more of a challenge to troubleshoot and correct The worst out come is that performance issues after a virtualisation project lead to the perception that VMware results in reduced performance and future confidence in VMware can be affected
- 4. Performance Basics • Virtual Machine Resources – CPU – Memory – Disk – Networking
- 5. Resource Maximums Host Guest Logical Processors 64 N/A Virtual CPUs N/A 8 Virtual CPU’s per Core 20 N/A Memory 1TB 256GB http://www.vmware.com/pdf/vsphere4/r40/vsp_40_config_max.pdf
- 6. Typical Host vSphere 1U Host CPU’s 2 x Quad Core Memory 32-64GB RAM Typical 3 VMs per core, 24VM’s per Host Each has 2GB of RAM = 48GB of RAM
- 7. Root Cause Analysis http://www.vmware.com/resources/techresources/10066
- 9. Monitoring Performance • Do not rely on guest tools, but – Can show high CPU, & Memory Utilisation – Measurement of Latency & throughput of Disk & Network Interfaces • Use the virtualisation layer, to diagnose cause: – Guest is unaware of virtualisation workload – The way in which guest OS’s account time is different – No visibility of available resources
- 10. Performance Analysis Tools • esxtop (service console only) • resxtop (remote command line utilities) • Performance graphs in vCentre
- 11. esxtop • esxtop can be run: – Interactively – Batch (eg. esxtop -a -b > analysis.csv) – Load batch into windows perfmon or MS Excel • Two keys to remember – H : help – F : fields to display
- 12. esxtop basics Host Resources Name of Resource Pool, Virtual Number of Worlds Machine or World
- 13. Performance Characteristics CPU Memory Networking Disk Slow Processing Slow Processing Packet Loss Log Stalls High CPU Wait Disk Swapping Slow Network Disk Queue Slow Application Performance Reduced User Experience Data Loss and Corruption
- 14. CPU ESX Scheduler Basic World States Read / Run / Wait CPU States Service Virtual Ready / Usage / Wait Console Machine Limits / Shares / Reservations
- 15. CPU High %RDY + High %User can imply over commitment esxtop •PCPU(%): CPU utilization •%USED: Utilization •%RDY: Ready Time •%RUN: Run Time •%WAIT: Wait and idling time
- 16. CPU VI-Client Used Time > Ready Time: Possible CPU over-committment Used Time Ready Time
- 17. CPU Further Investigation %MLMTD shows this VM has been limited
- 18. CPU Further Investigation High ready time caused by CPU resource limit
- 19. VMware Memory Management • Transparent Page Sharing • VMware Tools Balloon Driver to force the VM to swap to disk • Virtual Machine Page File
- 20. Memory Ballooning vs. Swapping Ballooning driver causes the host to swap pages that it chooses to disk ESX Swapping will swap any pages to disk.
- 21. Memory • Ballooning can be disabled (0 value) or controlled on a per Virtual Machine basis using: sched.mem.maxmemctl • Default is set to 65%, can be controlled at host level. • Only is an issue in resource contention scenarios. (or VM’s with low latency eg Citrix)
- 22. Memory - Host VI Client shows memory usage of the host. This is calculated as “consumed + overhead memory + Service Console”. Performance charts are a very good way of showing the Virtual Machine memory breakdown. • Consumed Memory • Ballooned Memory • Shared Memory • Swapped Memory
- 23. Memory - Guest Host Memory = Consumed + Overhead Memory Guest Memory = Active Memory for Guest OS
- 24. Memory – Guest Overhead
- 25. Memory Virtual Machine Memory Metrics – VI Client Metric Description Memory Active (KB) Physical pages touched recently by a VM Memory Usage (%) Active memory / configured memory Memory Consumed (KB) Machine memory mapped to a virtual machine, including its portion of shared pages. Doesn’t include overhead memory Memory Granted (KB) Physical pages allocated to a virtual machine. May be less than configured memory. Includes shared pages. Doesn’t include overhead memory. Memory Shared (KB) Physical pages shared with other virtual machines Memory Balloon (KB) Physical memory ballooned from a virtual machine Memory Swapped (KB) Physical memory in swap file (approx. “swap out – swap in”). Swap out and Swap in are cumulative Overhead Memory (KB) Machine pages used for virtualisation
- 26. Memory Host Memory Metrics – VI Client Metric Description Memory Active (KB) Physical pages touched recently by the host Memory Usage (%) Active memory / configured memory Memory Consumed (KB) Total host physical memory – free memory on host. Includes Overhead and Service Console memory Memory Granted (KB) Sum of physical pages allocated to all virtual machines. Doesn’t include overhead memory. Memory Shared (KB) Physical pages shared by virtual machines on host Shared Common (KB) Total machine pages used by shared pages Memory Balloon (KB) Machine pages ballooned from virtual machines Memory Swap Used (KB) Physical memory in swap file (approx. “swap out – swap in”). Swap out and Swap in are cumulative Overhead Memory (KB) Machine pages used for virtualisation
- 27. Memory PMEM: Total physical memory breakdown esxtop VMKMEM: Memory managed by vmkernel COSMEM: Service Console memory breakdown PSHARE: Page sharing statistics SWAP: Swap statistics MEMCTL: Balloon driver data
- 28. Memory esxtop / VI Client metrics : Virtual Machines VI Client esxtop Active Memory TCHD Memory Usage %ACTV Consumed Memory N/A Memory Granted N/A (SZTGT and CMTTGT represent memory scheduler targets) Memory Shared SHRD (+SHRDSVD per VM). Must enable COW stats in ESXTOP Memory Balloon MCTLSZ Memory Swapped SWCUR (SWR/s & SWW/s are rates) Overhead Memory OVHD & OVHDMAX
- 29. Memory esxtop / VI Client metrics : Host Usage VI Client esxtop Memory Active N/A (try /proc/vmware/sched/mem-verbose) Memory Usage N/A (try /proc/vmware/sched/mem-verbose) Memory Consumed PMEM total – PMEM free Memory Granted N/A (SZTGT and CMTTGT represent memory scheduler targets) Memory Shared PSHARE (shared) Memory Shared Common PSHARE (common) Memory Balloon MEMCTL Memory Swap Used SWAP (r/w and w/s are rates) Overhead Memory OVHD & OVHDMAX
- 30. Memory VI Client memory usage graph
- 31. Memory Troubleshooting Memory usage issues
- 32. Networking •Switch Assisted Teaming (IP Hash) •VLAN Trunking •Flow Control (full) •Speed & Duplex (1000Mb / Full) •Port Fast •BPDU Disabled •STP Disabled •Link State Tracking •Jumbo Frames Network configuration is more likely to blame than resource contention
- 33. Networking esxtop Transmit and Receive in Mb/s Transmit and Receive in Packets
- 34. Networking esxtop Dropped Packets Transmit Drop Packets Received
- 35. Disk Varying Factors • File system performance • Disk subsystem configuration (SAN, NAS, iSCSI, local disk) • Disk caching • Disk formats (thick, sparse, thin) ESX Storage Stack •Different latencies for different disks •Queuing within the kernel K: Kernel D: Device G: Guest
- 36. Disk VI Client statistics Quite Coarse Statistics • Disk read / write rate (KB/s) • Disk usage: sum of read BW and write BW (KB/s) • Disk read / write requests (per 20s interval) • Bus resets / Command aborts (per 20s interval) •Per LUN or aggregated stats
- 37. Disk esxtop statistics Aggregated stats similar to VI Client • Disk read / write per sec (READS/s, WRITES/s) • MB read / write per sec (MBREAD/s, MBWRTN/s) Latency Statistics • Kernel Average / command (KAVG/cmd) • Device Average / command (DAVG/cmd) • Guest Average / command (GAVG/cmd) Queuing Information • Adapter Queue Length (AQLEN) • LUN Queue Length (LQLEN) • VMKernel (QUED) • Active Queue (ACTV) • %Used (%USD = ACTV/LQLEN)
- 38. Disk SAN Rough Estimates Purely looking at a single ESX host, roughly: Throughput (in MBps) = (Outstanding IOs * Block size in KB) / latency in msec FC, rough maximums: Effective Link Bandwidth = ~80/90% of Real Bandwidth Effective (2Gbps) = 200 – 230 MBps Effective (4Gbps) = 410 – 460 MBps Effective (8Gbps) = 820 – 920 MBps iSCSI / NFS / FCoE, rough maximums: Effective Link Bandwidth = ~70/80% of Real Bandwidth Effective (1GigE) = 90 – 100 MBps Effective (10GigE) = 900 – 1000 MBps
- 39. Disk Desired Latency Calculations Desired Larency in msec <= (Outstanding IOs * Block size in KB) / Throughput per host Example: Number of Hosts: 16 Effective Link Bandwidth: 90 MBps Throughput per host: 90 / 16 = 5.6 MBps Desired Latency: (32 * 32) / (5.6) = 182.86 msec Workload Cached Sequential Read Cached Sequential Write Desired Latency (msec) 182.86 182.86 Observed Latency (msec) ~350 ~180 Throughput Drop? Yes No Throughput (MBps) ~45 ~90
- 40. Disk SAN Cache enabled VI Client High throughput SAN Cache disabled Poor throughput
- 41. Disk esxtop Latency is quite high After enabling cache, Latency is reduced
- 42. Virtual Machine Optimisation Deploy all machines from an optimised template! • VMware tools MUST be installed • The disks MUST be block aligned to the storage (even when using NFS and SAN) • Where possible, always separate data disks from OS disks • Windows performance settings should be optimised for application performance • Guest operating system timeouts should be set as defined by the SAN vendor • Pagefile should be separated where appropriate (this can impact VMware SRM however) • Unused Windows services should be disabled (wireless config, print spooler, audio, etc.) • Last access update time should be disabled (unless where required) • Logging of the VM should be disabled (only enabled for troubleshooting) • Remove any unused virtual hardware (floppy drives, USB, etc.) • Disable screen savers and power saving features, including logon screen saver • Enable Remote Desktop, avoid using the VI Client for remote administration • Install standard applications into template (bginfo, AntiVirus, any host agents, etc) • Multiple-CPU’s should be allocated sparingly
- 43. Virtual Machine Optimisation Block alignment is vital to good disk performance!
- 44. Command Action esxtop space Update the display ? Show the help page Command Options q quit when inside esxtop f/F Add or Remove columns from the display o/O Change the order the display is sorted s change the update interval # change the number of instances to display W Write configuration to file e Expand / Rollup CPU Stats V View only VM instances L Change the length of the NAME field m Display memory statistics n Display network statistics i Display interrupt statistics d Display disk adapter statistics u Display disk device statistics v Display disk VM statistics
- 45. esxtop Command Line Options from the console Command Action -b batch mode -l locks the objects available in the first snapshot -s enables secure mode -a show all statistics -c sets the configuration file -R enables replay mode (used with “vm-support –S”) -d sets the update interval -n runs esxtop for n iterations
- 46. esxtop Expand the default window size for your session to get all statistics
- 47. vm-support Creates a packaged zip file containing the following sections: • boot • contains the grub configuration • etc • contains the Console OS configuration files (cron, tcpwrappers, syslog, etc) • proc • contains much of the hardware configuration modules and variables • tmp • contains a lot of the ESX specific configuration output • var • contains log files and any core dumps • vmfs • contains the structure of the VMFS datastores • esx3-installation (where appropriate) • contains a copy if the previous esx3 configuration variables
- 48. vm-support Using vm-support to extract performance information: vm-support –S –d <duration> -i <interval> <duration> and <interval> are in seconds The output from this can then be replayed in esxtop for review after it has been extracted. esxtop –R <path_to_vm-support_output>
- 49. Service Console Performance •Multiple Service Console networks – for network resiliency •Increased Service Console memory – upto 800MB •Use host agents supplied by your vendors •Make storage recommended tweaks such as HBA Queue Depth and IO timeouts •Minimal use of the VI Client console – RDP or SSH instead •Properly sized vCenter server – 64bit OS where possible
- 50. Resource Groups Dynamically reallocate resource shares Additional VM, shares allow you to over- commit resources and have a graceful re-allocation Remove a VM and exploit extra resources across all remaining VM’s
- 51. Design Guidelines • Full Resilience / Multiple paths • Standard configuration across all aspects (ESX, Storage, Networking, etc.) • Standard naming conventions • Learn from others mistakes • Follow guidelines from vendors best-practices • Rule out the basics before requesting support
- 52. Capacity Planner & P2V Cautions and Limitations • Peak CPU usage can sometimes be misleading • Back-end storage system performance • P2V machines will require block-aligning to the storage • P2V machines will still require guest OS optimisation
- 53. Conclusion • Performance issues can often be traced with simple root cause analysis using basic tools (VI Client / esxtop) • Performance tools help diagnose issues and help rule out non- issues • Performance tools are useful in different contexts, not always either/or • Real-time data and troubleshooting: esxtop • Historical data: VI Client • Coarse resource / cluster usage: VI Client • Detailed resource usage: esxtop • Combine information from various tools to get a complete picture • Always benchmark your systems first so you not what the optimal performance is that you can receive
- 54. Reference Articles • http://www.vmware.com/pdf/esx3_memory.pdf • http://www.vmworld.com/docs/DOC-2370 • http://blogs.vmware.com/performance/ • http://communities.vmware.com/docs/DOC-5420 • http://kb.vmware.com/kb/1008205 • http://communities.vmware.com/community/vmtn/general/performance • http://www.vmware.com/products/vmmark/ • http://www.vmware.com/pdf/vsphere4/r40/vsp_40_san_cfg.pdf • http://www.vmware.com/pdf/vsphere4/r40/vsp_40_iscsi_san_cfg.pdf • http://www.vmware.com/pdf/vsphere4/r40/vsp_40_resource_mgmt.pdf • http://www.vmware.com/pdf/GuestOS_guide.pdf • http://www.vmware.com/resources/techresources/10066 • http://www.vmware.com/resources/techresources/10059 • http://www.vmware.com/resources/techresources/10062