The greatest challenge to any thinker is stating the problem in a way that will allow a solution

Bertrand Russell

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On 30 Jun 2011

Installation, VMware

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This post covers what you need to do to be able to run an ESXi3 server from a USB stick (if you’re installing ESXi 4 then you don’t need to do this, the VMware installer will detect the USB stick (or SD card) and install to it).

Note that while in theory an ESXi server makes very little use of the storage its running from, there is an important exception.  ESX3 HA will write to the storage, and in HA enabled clusters its possible for USB keys to become worn out.  This typically rears its head when trying to add/remove a server to an HA cluster, and this operation fails.  There are ways around out (not least replacing the USB key) and I’ll probably post on this later in a more general HA problems post.  Note that this problem is limited to ESXi3, ESXi4 HA is much more forgiving to the ESX’s storage.

So why do it?

When an ESXi server boots up, it expands its software image into a RAMdisk, and then runs from there.  Only config changes, etc, get written to its storage, so in general its doing sweet FA.  So to spend more than a couple of quid on proper disk (plus the power it will drain), seems pointless.  And after all, the whole point of virtualisation is squeezing every last bit of use out of every penny.

Required software etc…

  • WinImagehttp://www.winimage.com/download.htm
  • DDhttp://www.chrysocome.net/dd
  • ESXi install ISO
  • Disk Cloner, eg G4U – http://www.feyrer.de/g4u/
    • Ideally use a cloner that ignores the actual disk contents and does a block by block copy, anything that tries to interpret the disk image may not copy it faithfully
  • You must be able to connect two image files remotely to your server (assuming your using blade ESXs) – a disk cloner CD ISO, and the image USB ISO (hint: use the floppy drive).

Creating the USB image file

  1. Open up the ISO with WinImage
  2. Extract the INSTALL.TGZ from the ISO
  3. Uncompress INSTALL.TGZ and locate .INSTALLusrlibvmwareinstallerVMware-VMvisor-big-3.5.0_Update_4-153875.i386.dd.bz2
  4. Uncompress VMware-VMvisor-big-3.5.0_Update_4-153875.i386.dd.bz2 so that you have VMware-VMvisor-big-3.5.0_Update_4-153875.i386.dd
  5. Create ISO image from DD image by using DD
    • dd bs=1M if=VMware-VMvisor-big-3.5.0_Update_4-153875.i386.dd of=esx3.5ihp-usbimage.iso

Deploying the USB image file

  1. Attach your disk cloner image to your server and boot
  2. Once the the server is booting to the CD ISO, attach the USB ISO
  3. List the available disks
    • list
  4. Identify the image disk (which is 750MB) and the USB disk (which will be whatever size your USB key is)
  5. Copy the image to the USB key
    • copydisk sd1 sd0
  6. Disconnect all images, reboot server, cross fingers
    • reboot

 


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