Explaining Why ESXi Installs Require Extra Space Besides The Hypervisor
August 27th, 2009 | 
Author: There have been a couple of bloggers this week that, while responding to Microsoft’s competitive analysis on Hyper-V versus ESX/ESXi footprints, have revealed some very interesting and helpful information about what exactly is contained in ESXi installations and on the bootable ESXi flash drive. For reference I’ll summarize a few posts and then link to a VM /ETC post from last year explaining why the ESXi .ISO is so large as well.
First, Nate from Techopsguys.com provides a realistic, and “colorful” at times view of the actual amount of space consumed by ESXi when you install it in Does size matter?. Read his post, but the condensed message and my interpretation of what Nate is saying is “VMware please stop telling people your ESXi hypervisor is so small when so much more space is required to install it.”
“ESXi v3.5 was unable to boot directly from SAN so I can’t tell with the same level of accuracy how big it is, (”df” says about 200MB) but I can say that our ESXi v3.5 systems are installed on 1GB USB sticks, and the image I decompressed onto those USB sticks is 750MB(VMware-VMvisor-big-3.5.0_Update_4-153875.i386.dd), regardless, it’s FAR from 32MB or even 75MB, at best it’s 10x larger than what they claim.”
If VMware ESXi 4 is so small, why is it so big? is a post by Eric Gray that explains why the 32 mb ESXi 3 and the 60 mb ESXi 4 hypervisors on bootable flash drives require a 1 GB drive.
“Not only does a 1GB flash device contain the ESXi hypervisor, it also provides VMware Tools for various supported operating systems and a copy of the vSphere Client which administrators can download and install to their workstations. These components are not executed by the hypervisor at all — they can be obtained through other means, but it is very convenient to have them right on the host.”
Gray’s post also provides GParted screen shots of showing the partition layout as well as an image of the directory listing of the tools, drivers, and vSphere Client.
ESXi is as small as VMware says it is… by Mike Laverick also similarly discusses the contents of ESXi flash drives. Laverick also points out that for roll back purposes, ESXi installations also maintain copies of the previous installed versions. When an upgrade goes wrong a local copy of the former working ESXi version can be quickly recovered to.
If your curious about VMware’s methodology for coming up with the hypervisor footprint calculations they base their claims on then check out the Virtual Reality Blog post Our position on hypervisor footprints, patching, vulnerabilities and whatever else Microsoft wants to throw into a blog post. Eric Horschman gives you the gorey details on ESXi disk partition sizes as well as direct replies to the several other topics Microsoft has competitive issues with.
“A df -h command will then show you that the total size of those compressed ESXi boot images in the directory corresponding to /bootbank is 59.3MB — somewhat less than the 70MB figure we’ve publicly stated. The other partitions in the listing are either loaded only in memory (/), or they are excluded per the rules above. Note that this is not just a stripped down ESXi installation, it is a fully capable ESXi host supporting all licensed vSphere features.”
Finally If ESXi is so small why is the download so big? is a post I wrote after talking to Amir Sharif, VMware Senior Product Manager about the reasons the ESXi .ISO download(s) are over 200 MB. Copying what I wrote in the original post:
Amir explained to me that the VMware ESXi downloads (both for installation media and patches) contain 4 major components. These components and their approximate sizes are:
- VMware ESXi (32 MB)
- VMware VI Client (48 MB)
- VMware Tools (120 MB)
- Global and regional server vendor value-add customization bits (30 MB)
It’s important to note that there are several versions of the VMware Tools depending on the target OS, and there are two different bundle types for Linux OSes (.rpm and .tgz). There are multiple versions of server vendor customization bits as well. Therefore, VMware’s completeness to include all of these items in a single download makes for a large .iso file. In case you noticed the math doesn’t match the current version’s download size, that is because the 4 component sizes are approximates and will change from version to version.
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