However, one limitation that some have discovered while using this lab-testing technique is the lack of ability to use snapshots with virtual ESX systems.  In fact, after taking a snapshot of a virtual ESX VM, you will see the system boot into the recovery shell like so:

Ouch.

Can we fix it?

I asked some super-smart engineers inside VMware about the issue, and of course they know all about it and how to make it work.

The solution is to enable an undocumented advanced configuration option on the physical ESX host like so:

In other words:

• Log into the console of the physical VMware ESX 4 host
• Run the following command: esxcfg-advcfg -s 1  /COW/PermitVmfsOnRedoHierarchy
• Verify the setting with the “get” flag: esxcfg-advcfg -g /COW/PermitVmfsOnRedoHierarchy

Do I even need to say that this stuff is not supported by VMware Global Support Services (GSS)?  Well, I just did.

Yes we can!

After executing that one command on your physical machine, take a snapshot and boot up your virtual ESX:

Everything works just like you need it to now — you can even create a snapshot hierarchy:

Now what?

Were you constrained by the lack of virtual ESX snapshots?  What interesting things will you use this for?

Related posts:

1. Half the VM reboots on Patch Tuesday
2. VMware vSphere 4 has a Snapshot Alarm
3. Hyper-V snapshots: not for production
4. IGT Part 5: Hyper-V snapshots are not gone until the VM is powered off

If you are not familiar with CapacityIQ (a.k.a. CapIQ or CIQ), it is an add-on management product for vCenter Server that assists in planning and managing virtualization resources.

CapIQ is very easy to deploy since it ships as a virtual appliance in OVF format — just load it onto an ESX host and perform a few simple configuration steps. It’s also simple to use since the user interface is a vSphere Client plug-in.  That means no additional web interfaces or user accounts to deal with — just a single pane of glass.

To learn more, check out the Evaluator’s Guide and other documentation.

Installation Experience

For those curious about the installation experience, here is an overview of the very simple procedure.

Upload the CapacityIQ VM using vSphere Client

Configure Credentials

The CapacityIQ appliance has two user accounts: root and ciqadmin.  When you first power on the VM, you will be prompted to enter passwords for those accounts.  Unlike some VM appliances, there are no default passwords involved.

Connect CapacityIQ to vCenter Server

After the appliance is finished booting, a URL will be shown on the console.  Open that with your browser and log in using the ciqadmin account.

Enter the address and credentials needed to connect to your vCenter Server:

vSphere Client Interface

After CapacityIQ is registered with your vCenter Server, restart your vSphere Client.  Verify that the plug-in has been installed automatically.

If everything is in order, you’ll find a new icon on the vSphere Client Home screen:

Views and Reports

CapacityIQ comes with a number of preconfigured views and reports, as seen here:

Related posts:

1. VMware vCenter Server 4.0 installation video
2. Installing vCenter on Linux Technical Preview
3. Red Hat Enterprise Linux is not Enterprise Virtualization
4. VMware vCenter Server 4 task and event retention

But what if you prefer to run ESX on ESX instead of Workstation?

You may be pleased to know that the GA build of ESX 4 allows installing ESX 4 as a virtual machine as well as powering on nested virtual machines — VMs running on the virtual ESX host.  You can even VMotion a running virtual machine from the physical ESX to a virtual ESX — on the same physical server!

VMware vSphere 4.1 UPDATE: VMware ESXi 4.1 has a keyboard issue when virtualized on an ESX 4.0 host.  In order to virtualize ESXi 4.1, the underlying host must be 4.1.  However, ESX 4.1 classic will work on ESX 4.0.

The extra tweaks to make it all work are minimal, and I will show you how without even opening up a text editor.

After installing ESX 4 onto your real hardware, configure as desired and enable promiscuous mode on a vSwitch:

Create a new VM with the following guidance (choose “Custom”):

• Virtual Machine Version 7
• Guest OS: Linux / Red Hat Enterprise Linux 5 (64-bit)
• 2 VCPUs, 2GB RAM
• 2 NICs – e1000
• LSI Logic Parallel
• New disk – reasonable size greater than 10GB for ESX classic

After you have the VM ready, simply attach a VMware ESX 4 ISO image, power on, and install ESX as a guest OS.

After installation, add the new virtual ESX to vCenter 4 and create a new VM.

If you do not need to run VMs on your virtual ESX, you can stop there.  However, if you try to power on that nested VM, you will see the following error:

To prevent this, just one tweak is needed:

• Shut down the virtual ESX VM
• Click Edit Settings
• Click the Options tab
• Click Advanced / General / Configuration Parameters…
• Click Add Row
• For the Name/Value enter: monitor_control.restrict_backdoor / TRUE

The above procedure is just an alternative to hand-editing the .vmx file — if you prefer to do it that way, feel free.

Now you are ready to power your virtual ESX VM back on, as well as the nested VMs.  This capability should come in handy as you start investigating the new features of vSphere 4.

UPDATE:  In order to take snapshots of a VM running ESX, a quick configuration change is necessary on the physical host .

You may be interested in this related post where a VM is migrated between the physical and virtual ESX hosts.

Related posts:

1. VMotion from physical ESX 4 to virtual ESX 4
2. Taking snapshots of VMware ESX 4 running in a VM
3. Idle RHEV Hypervisors save power?
4. Pentacore CPUs in VMware ESX 4