rvc – Page 3

Quick Tip - lldpnetmap, a handy utility to map pNic to pSwitch on ESXi

05.20.2014 by William Lam // 8 Comments

Last week while attending VMware's R&D Innovation Offsite (RADIO), I ran into Christian Dickmann, who as many of you know works on the VSAN team. During our discussion, he mentioned a nifty little utility called lldpnetmap that he had used recently. This utility is found within the ESXi Shell and provides a quick and easy way to display the mapping between an ESXi hosts physical network interface to the physical switch they are connected to using LLDP (Link Layer Discovery Protocol). This is similar to what Cisco's proprietary discovery protocol (CDP) provides, but only details about the physical switch.

CDP has been supported with vSphere Standard Switches for quite sometime now, but LLDP support was only added recently with the introduction of the vSphere Distributed Switch. Chris Wahl has a great article here on why you should enable either CDP/LLDP and the benefits you get with it. For customers who are running non-Cisco switches, lldpnetmap is a great way to quickly figure out which physical switch your ESXi hosts are connected to, especially useful during troubleshooting where every minute counts.

There are actually two ways in which you can run the lldpnetmap utility. The first method is by running it within the ESXi Shell using the following command:

lldpnetmap

The command takes about about 30-60 seconds to run and if successful, you should see the name of the physical network switch and the vmnic (pNIC) that they are connected to.

Here is a screenshot of what that output looks like:

The second method is actually how Christian had been using the command which is through RVC. Using the vsan.lldpnetmap command, you can specify an individual ESXi host or an entire vSphere Cluster. Even though the command is under the VSAN namespace, you do not need to have VSAN enabled to use the command.

Here is a screenshot of what that output looks like:

Note: If you do not see any output, you are most likely connected to a Cisco switch or to a non-managed switch that does not support LLDP.

This is one utility I will be sure to remember the next time I need to troubleshoot a networking issue. Thanks for sharing this handy tidbit Christian!

How to run the VSAN Observer in "collection" mode in the background?

05.18.2014 by William Lam // 1 Comment

The VSAN Observer is a very powerful tool that allows you to get in-depth performance analysis of your VSAN environment. One of the really useful feature is the ability to run the VSAN Observer in "collection" mode by using the --generate-html-bundle option. Something that I have noticed when running the VSAN Observer in collection mode is that you not close the current SSH session, else the collection will stop. I have even tried running the VSAN Observer using RVC's not very well known "script" feature and then back-grounding the process, but after a minute or so the collection also just stops.

The only workaround that I have found is by using Screen, a full-screen windows session manager usually found on most Linux/UNIX and Mac OS X systems. Having used Screen in the past life as a Systems Administrator, I can say it is an extremely useful tool when needing to perform long running tasks and not have to worry about your SSH session being disconnected. You can start a session, disconnect and then re-connect at a later time to monitor the progress.

If you are on a Mac, then Screen should have already been installed. Below are the steps to run the VSAN Observer in the VCSA using Screen:

Step 1 - Start screen and give the session a name such as "VSAN-Observer" for example:

screen -S VSAN-Observer

Step 2 - SSH to your VCSA and login to RVC and start the VSAN Observer using the collection mode as you normally would. For step by step instructions, check out Rawlinson Rivera's article here on setting up the VSAN Observer.

Step 3 - Once the VSAN Observer is running, enter the following key combinations which will detach your Screen session:

Crtl+a d

Step 4 - To list the available Screen sessions, you can run the following command:

screen -list

Step 5 - To re-attach to your Screen session, you will need to specify the session name. In our example, it was called VSAN-Observer:

screen -r VSAN-Observer

An alternative to Step 2, instead of running the VSAN Observer interactively, I actually prefer to run the VSAN Observer using RVC's script option. It is just less typing for me and makes it easy to collect stats across multiple VSAN environments

To do so, you will need to create a script file that contains the following:

# William Lam
# www.virtuallyghetto.com
# RVC script for running VSAN Observer

datacenter_name = "VSAN-Datacenter"
cluster_name = "VSAN-Cluster"
vsan_html_output_directory = "/storage/core"
vsan_observer_runtime = "1"

# Do not edit beyond here #

puts "Enabling VSAN Observer collection for: #{cluster_name} ..."
rvc_exec("vsan.observer --run-webserver --force --generate-html-bundle #{vsan_html_output_directory} --max-runtime #{vsan_observer_runtime} /localhost/#{datacenter_name}/computers/#{cluster_name}")

The RVC script option actually accepts a Ruby script to execute and if we take a look at the script, we are just passing some arguments to the vsan.observer command.

To use the RVC script instead of interactively logging in, you can run the following command:

rvc -s [SCRIPT-NAME] [USERNAME:PASSWORD]@localhost

I think a nice feature enhancement to the VSAN Observer is the ability to automatically background the collection process without having to rely on the existing SSH connection, perhaps this is something Christian may consider for a future update to RVC 🙂 In the meantime, this is a pretty decent work around

Extending RVC to support renaming VM Storage Policies

03.18.2014 by William Lam // 1 Comment

I was recently using RVC (Ruby vSphere Console) to setup one of my VSAN lab environments and I had noticed that in the SPBM namespace, that you could create and delete a VM Storage Policy, but you could not rename an existing one. The great thing about RVC is that it is very extensible and I thought it would be useful to have a spbm.profile_rename command, so I decided to build it!

The management of VM Storage Policies is performed through the SPBM API and there is a method called PbmUpdate() which allows you to rename an existing VM Storage Policy. In my environment, I exclusively use the VCSA (vCenter Server Appliance) and in the /root directory, you should see a .rvc directory. To extend the SPBM namepace, you just need to create a new file called spbm.rb which should contain the following snippet of code:

opts :profile_rename do
  summary "Rename a VM Storage Profile"
  arg :profile, nil, :lookup => RbVmomi::PBM::PbmCapabilityProfile
  arg :name, "New name", :type => :string
end

def profile_rename profile, name
  _catch_spbm_resets(nil) do
    pbm = profile.instance_variable_get(:@connection)
    pm = pbm.serviceContent.profileManager
    spec = PBM::PbmCapabilityProfileUpdateSpec(
      :name => name,
    )
    pm.PbmUpdate(:profileId => profile.profileId, :updateSpec => spec)
  end
end

Once you have saved the file, you can now connect to RVC and you should see a new command called spbm.profile_rename which takes an existing VM Storage Policy and the new name of the policy.

Here is an example of what that would look like where I have a VM Storage Policy called "Platinum" and I want to rename it to "Adamantium":

spbm.profile_rename localhost/Datacenter/storage/vmprofiles/Platinum/ Adamantium