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Quick Tip - Correlating VMFS Datastore to Storage Device Using ESXCLI

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There was a question on Twitter this morning from AJ Kuftic on whether it is possible to display the mapping of a VMFS Datastore to its respective storage device using ESXCLI. Josh Coen beat me to the answer this morning, but yes it is possible using ESXCLI. I thought I still share this quick tip as it may not be obvious, especially when you need this information while performing a storage maintenance or troubleshooting with your storage administrator.

For those of you who are familiar with the legacy esxcfg-* commands, this information can be retrieved using the following command:

esxcfg-scsidevs -m

You can also retrieve this same information by using the following ESXCLI command (can be executed remotely as well):

esxcli storage vmfs extent list

As you can see from both screenshots, we can easily identify the name of the VMFS datastore and the specific storage device it is mapped along with other pieces of information. I prefer the ESXCLI method as it is nicely formatted along with the title header for each property.

A Hidden vSphere 5.1 Gem - Forwarding Virtual Machine Logs (vmware.log) to Syslog Part 2

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In Part 1 I showed how you can forward virtual machine logs to ESXi syslog using an advanced virtual machine setting that was introduced in vSphere 5.1. A caveat with this solution is that the ESXi syslog file contains both system logs as well as virtual machine logs which is not very ideal from an isolation perspective. With virtual machine logs being quite verbose, if you are not forwarding logs to a remote syslog server, important system events can easily be rotated out of the local logs.

To work around this caveat, we can create a new logger specifically for handling virtual machine logs within the ESXi syslog client. You can view the existing logger types by looking in /etc/vmsyslog.conf.d directory. You will need to create a new logger configuration file which I named vmx.conf and it should contain the following:

[vmsyslog-logger]
# unique id for this logger
id = vmx
# description of this logger
descr = VMX Logs
# idents this logger is interested in
idents = vmx
# output file (e.g. foo == /var/log/foo.log)
file = vmx
# file logger class
fclass = FileLoggerSyslog
# network logger class
nclass = NetworkFilterSyslogTimestamp

Here is a screenshot of of my configuration file and noticed the highlighted text in yellow is what needs to be modified:

Note: Ensure that idents property matches the vmx.log.syslogID string specified for your virtual machines. This also means you will not be able to specify the virtual machine's name for the advanced setting, but will need to keep it generic so it can be filtered by the logger.

Once you have saved the vmx.conf configuration file, you will need to reload the ESXi syslog client for the changes to go into effect by running the following ESXCLI command:

esxcli system syslog reload

You now should see a new log file in /var/log called vmx.log which will contains only virtual machine logs:

If your ESXi host is forwarding its logs to vCenter Log Insight, you can easily create a filter for the keyword "vmx" in the log source or whatever string you decided to set it to if you are not using the default.

One final caveat to be aware of now is that the custom syslog logger (vmx.conf) will not persist after a system reboot. To preserve this file, you can either automatically re-create the file during bootup and reload syslog client using this article here OR create a custom VIB using this article here.

Whitepaper: Migrating From VIX API to the vSphere Guest Operations API

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The VMware VIX API in my opinion is still one of the most powerful and undervalued API's that is available to customers and partners for Virtual Machine guest operating system Automation. The VIX API allows you to perform guest operations such as starting/stopping an application, file/directory manipulation, uploading/downloading files all within the guest operating system without requiring any network connectivity to the Virtual Machine. This is all made possible through the use of VMware Tools that is running inside of the Virtual Machine and operations are only performed after a user of the guestOS is properly authenticated.

Guest Operations using vSphere API

The use cases for such an API are endless:

  • Network reconfiguration (Re-IP for DR or miss-configuration)
  • Operating System configurations
  • Application configurations or deployments (example of this)
  • Backup/Restore for individual files
  • Downloading log files for troubleshooting
  • The list goes on ....

The VIX API was first introduced as a separate client API supporting VMware's hosted products such as VMware Fusion, Workstation and Player and later supported VMware vSphere. The API was quite popular for the hosted products and with the release of vSphere 5.0, the VIX API was finally integrated into the vSphere API to provide a single API that could manage all aspects of vSphere as well as these new guest operations APIs for your Virtual Machines. With this integration, these new APIs are now known as the vSphere Guest Operations API.

If you are familiar with the VIX API and would like to move or migrate to using the new Guest Operations API within vSphere, there is a really useful whitepaper that I recently came across called Transporting VIX Guest Operations to the vSphere API that provides a nice mapping of the API methods between the VIX and new vSphere Guest Operations API. The whitepaper also includes various code samples using Java, PowerCLI cmdlets and vSphere SDK for Perl to demonstrate the new Guest Operations APIs.

I think every vSphere administrator or developer should be familiar with the capabilities of the VIX and Guest Operations API and how it can help them further automate and manage your guestOSes and the applications that run inside of them.

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