Virtualization Pro

Mar 3 2009   4:41PM GMT

Collecting diagnostic data from hosts and vCenter Server

Eric Siebert Eric Siebert Profile: Eric Siebert

A recent VMware Knowledgebase article has a great matrix for collecting diagnostic information for many VMware products. One product that was missing from the lineup, however, was VMware ESXi, so I thought I would cover the methods for collecting diagnostic information from an ESXi host in addition to covering the collection methods for VMware ESX and vCenter Server.

Typically when you open a support case with VMware they will want you to generate diagnostic bundles that they can use to diagnose your issue. Collecting this diagnostic information from ESX/ESXi hosts and vCenter Servers consists of packaging together various log and configuration files as well as command output and performance data that can be used for troubleshooting purposes. There are two ways to do this; you can use the vm-support script that is run from the ESX service console/ESXi management console or you can use the Export Diagnostic Data option in the VMware Infrastructure Client (VI Client).

The vm-support script can be run in the ESX service console, but you can also run it in the ESXi hidden technical support management console. (For information on accessing the ESXi hidden console see How to access the VMware ESXi hidden console.)

When you run the vm-support command without any options, the command creates a single .tgz file containing thousands of files that can be extracted and viewed to troubleshoot problems. The size of this file will vary depending on various factors including how many VMs are on your host and the typical size is around 20 MB. Before running the vm-support script you should switch to the /tmp directory as the .tgz file is created in the directory where you run the script. Once the file is created you can copy it to your workstation using a program like WinSCP and extract it using either the Linux tar command or an application like WinZip. These files are very useful to VMware support for troubleshooting your problem. You can also specify parameters when running vm-support to collect specific information or do certain tasks.

Below are some of the most commonly used parameters:

  • -n – causes no core files to be included in the tar file
  • -s – take performance snapshots in addition to other data
  • -S – take only performance snapshots
  • -x – lists world ids (wid) for running VMs
  • -X <wid> – grab debug info for a hung VM
  • -w <dir> – set working directory for output files
  • -h – displays help for command usage and available options

If you do not want to use the command line to collect this information you can use the VI Client. You can connect to either a single ESX or ESXi host, or you can generate diagnostic bundles for multiple hosts by connecting to a vCenter Server. Once you connect, select File from the top menu, Export, and finally the Export Diagnostic Data option. Optionally, you can click the Administration button, select the System Logs tab and click the Generate Diagnostic Data button. Or, to collect vCenter Server only diagnostics, you can use the Generate VirtualCenter Server log bundle – FULL option while directly on the vCenter Server (Start > All Programs > VMware > Generate VirtualCenter Server log bundle – FULL).

When connected to a standalone host you can only opt to select a directory on your workstation to store the file. When connected to a vCenter Server you can collect diagnostic data from multiple hosts as well as the vCenter server. Once you select the hosts, a task will be created in the VI Client, the vm-support script will run on the hosts you selected, and the resulting .tgz files will be downloaded to your workstation. If you also chose to include the vCenter Server it will create a separate diagnostic bundle for it in a zip file format.

As these diagnostic bundles also contain configuration files it is a good idea to run them periodically even if you do not have a problem so you have a backup of your host configuration. Just be careful that you clean up the .tgz files on your hosts afterwards to avoid filling up your disk partitions.

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