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New way of enabling and disabling services using vSphere 4.1

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While checking out the PlanetV12n feed, I noticed a new video from David Davis about the new vSphere 4.1 Tech Support Mode. In the short video, David goes over the new method of enabling "hidden" unsupported Busybox Console, also known as Tech Support Mode. In the past, you had to be on the console of your ESXi host, type ALT+F1, and then "unsupported" to gain access. Once in, to enable remote SSH access or Remote Tech Support Mode, you had to edit /etc/inetd.conf and restart inetd service. This was pretty tedious if you needed access for a short period of time. In the video, David goes over the new method showing how it can be done using the DCUI and the old method is no longer required.

What surprised me after watching the video was that he did not mention the other method of enabling and disabling Tech Support Mode both local and remote. One issue I had with past releases of ESXi is that you could restart some services such as ntp or vmware-vpxa via the vSphere API, but others were just not available. In vSphere 4.1, VMware introduces a few new services around their Likewise Active Directory integration but also includes controlling both local and remote Tech Support Mode as well as DCUI itself.

These services can be enabled and disabled using the vSphere Client, here is a screenshot:

To enable or disable TSM, just click on the service and then click on options:

You will then have the option to configure the startup policy including enabling or disabling the service:

If you needed to perform this operation against one or two host, it is not that big of a deal. Though if you needed to enable remote Tech Support Mode (SSH access) across few dozen hosts, then can still be tedious. Luckily I wrote a script (hostServiceMangement.pl) last year that allowed you to enable and disable supported services using the vSphere API. Without any modifications, it supports vSphere 4.1 and can take advantage of the new services that are available for control.

Here is an example of listing the services on an ESXi 4.1 host:

Here is an example enabling remote Tech Support Mode:

Here is an example of disabling remote TSM:

The script can be executed on a host that has vCLI 4.1 installed or on vMA 4.1 and can bulk update a list of ESX/ESXi host or individual host. For more details, please check out the documentation for hostServiceManagement.pl.

Script - Automate VAAI Configurations in vSphere 4.1 (vaaiHWAccelerationMgmt.pl)

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With the release of vSphere 4.1, we finally get to see the first revision of the vStorage API for Array Integration (VAAI) features. This initial release provides the following SCSI driver primitives with VAAI supported storage arrays:

  • Write Same/Zero - Eliminating redundant and repetitive write commands, tells array to repeat via SCSI commands.
  • Full Fast/Copy - Leverage array to mass copy, snapshot and move blocks via SCSI commands.
  • Atomic Set and Test - Stop locking LUNs and start locking blocks.
  • Thin Provisioning Stun - Reporting array TP state to ESX.

The above definitions were taken off of an EMC presentation found here. VMware has also published a new VMware KB article regarding VAAI FAQ, take a look here at KB1021976.

Though these features are not specific to any one storage array vendor, the vendors themselves are required to implement these primitives within their array OS software for them to be available. If all prerequisites are met, and you have an ESX or ESXi host running on vSphere 4.1 and VAAI supported storage array, these new storage operations will now offload to the array versus running within the VMkernel.

However, if you do not have an array that supports VAAI, the new version of ESX and ESXi will still try to use these features. As I understand from an earlier discussion of VAAI, there is one additional operation that is performed and it's impact is supposed to be insignificant (please correct me if I'm wrong). Though if you would like to disable these VAAI features or would like to see the difference between a non-VAAI and VAAI operation, it is controlled with the following three advanced host configurations.

VMFS3.HardwareAcceleratedLocking - Atomic Test and Set
DataMover.HardwareAcceleratedMove - Full/Fast Copy
DataMover.HardwareAcceleratedInit - Write Same

By default, all three of these configurations are enabled with a default installation of vSphere 4.1. The following vSphere SDK for Perl script allows a user to enable or disable VAAI configuration on a set of hosts defined in an input file. The script allows you to connect to vCenter if your hosts are being managed by vCenter or directly to a specific ESX or ESXi host and provide the following parameters:

--hostlist = Lists of ESX(i) hosts to perform operation _IF_ they're being managed by vCenter (default is ALL hosts in vCenter)

--operation = Operation to perform (query|enable|disable)

Download: vaaiHWAccelerationMgmt.pl

Here is an example of the host input file:

[[email protected] scripts]$ cat hosts
esxi4-2.primp-industries.com
esxi4-3.primp-industries.com
Here is an example of querying for VAAI configurations:

Here is an example of disabling VAAI configurations:

Here is an example of disabling VAAI configurations:

For more information about vStorage APIs, take a look here.