Yellow Bricks

by Duncan Epping

ESX

Change the license server from the Service Console

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Got a question today on how to change the licensing server from the Service Console or how to add the license server via a scripted install. Of course “vmware-vim-cmd” is the keyword here. If you want to use a license server you will need to use the first option, if you want to add a license file you will need to use the second option:

  1. vmware-vim-cmd vimsvc/license --source server
  2. vmware-vim-cmd vimsvc/license --source file

Don’t you just love “vmware-vim-cmd”….

255GB Memory Limit for VMs with vSphere

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This afternoon @Stevie_chambers published something on twitter on memory limits of vSphere VMs. This was a recap of a question asked on a VMware internal mailinglist, here’s what Steve posted:

Why has a vSphere VM max mem 255GB? VMFS block size of 1MB = 256GB max – 0.4MB VM state = 255.6MB rounded down to 255GB – from Ole@VMware

In other words, the maximum memory size for a vSphere VM is 255 GB. This is the maximum memory size because a swap file needs to be created as well. This swap file cannot exceed the maximum file size of a 1MB blocksized VMFS volume. Max file size = 256GB – VM state(roughly 400MB)=255.6GB. For safety this has been rounded down to 255GB. Which at first sounds like a weird amount but actually makes sense when you read the explanation.

By the way, Steve has recently started a blog: View Yonder. Welcome to the blogosphere!

License server VM down, now what?

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On twitter John Troyer retweeted a question a couple of days ago which basically came down to the following: When your VM which contains the license server goes down and has been down for longer then 14 days you will not be able to actually boot it up. This is because the grace period has expired.

As a VMware PSO Consultant my recommendation is to make sure you always have a “host based” license file laying around. In a normal situation you don’t need to use it. But in a situation like this it will be very useful because you can just change the license to a host based license instead of a “license server”. This would enable you to actually boot up the License VM. When booted up you could easily revert the changes again and point to your license server again.

Running vSphere within Workstation will take up a lot of memory…

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As some of you noticed, when you install vSphere(ESX) within a VM you will need at least 2GB to get the installer started. Even when it has finished installing you can’t reduce the memory because the following error will occur:

I couldn’t find a way of  pre-adjusting the memory requirements but there’s a way to change this behavior and to downsize the memory when the installation has finished. Keep in mind this is, as far as I know, not supported… it’s only to be used to run ESX within VMware Workstation for your demo / test environment. I personally use it for running 2 ESX servers and vCenter within VMware Workstation on my 4GB laptop. (That’s what I actually use to create screenshots and prepare blog articles.)

ESX:

  1. Install vSphere(ESX) with at least 2 GB memory
  2. Login to the Service Console and type the following: 
    vi /etc/vmware/init/init.d/00.vmnix
  3. Change the following line to the desired value: 
    RequiredMemory=2064384
  4. Shutdown the virtual machine and change the VMs memory and boot it up!

Thanks Mark for the comment on ESXi:

  1. Install vSphere(ESXi) with at least 2 GB memory
  2. Login to the console via the “unsupported” method.
  3. Edit the file /etc/vmware/esx.conf and add the following line: 
    /vmkernel/minMemoryCheck = “false”
  4. Save the file and shutdown ESXi, change the memory and boot it up!

Don’t use any other editor than “vi”, there are multiple reports of nano wrecking the layout of the file which leads to an unrecoverable error during booting.