Yellow Bricks

by Duncan Epping

Lessons Learned

ESXi and Boot From SAN support

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Rodos just reported on twitter that it looks like Boot From SAN is supported for ESXi. Unfortunately the KB article Rodos refers to in his tweet, kb.vmware.com/kb/1015000, is incorrect and Boot From SAN is not supported for ESXi. I’ve already reported this internally and hopefully the KB article will be fixed soon. The correct statement can be found in the install guide and is as follows:

Installing on a Fibre Channel SAN is supported experimentally. Do not attempt to install ESXi with a SAN attached, unless you want to try this experimental feature.

Source: ESXi Installable and vCenter Server Setup Guide (page 20)

For those interested in what “experimental” actually means, read this section on the VMware website.

Remove the ESXi web welcome screen

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I received a question from a customer who wanted, for security reasons, to remove the ESXi web welcome screen. This is the screen that enables you to download the vSphere Client and RCLI and even browse datastores.

I’ve tested it and removing (or renaming) the following file will lead to a blank page when the ESXi host is accessed via http(s):

/usr/lib/vmware/hostd/docroot/index.html

<edit>

William Lam created another work around which is definitely a more elegant solution: Remove the ESXi web welcome screen.

</edit>

ESXi – lessons learned part 4

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I was just figuring something out from the command line on an ESXi 4.0 host. I needed to mount a partition but a regular “mount” did not work so it took me a couple of seconds to realize why. The solution was simple and similar to the regular mount command:

/usr/bin/busybox mount

also might come in handy:

/usr/bin/busybox fdisk -l

Busybox… indeed, that’s what is being used under the hood and that’s what needs to be used for specific commands. Just run /usr/bin/busybox and you will see which commands you will have to your disposal. Another command I often use when working on the ESXi console is “vim-cmd”. Remember these…

ESXi – lessons learned part 3

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This is probably one of the last blog articles this year as I’ve got two weeks of holiday! I wish you all a merry Christmas and a happy New Year! Let’s cut the crap, and start with why you are reading this… ESXi Lessons Learned:

I’ve been looking into creating an unattended install for ESXi. As mentioned in Lessons Learned part 2 this is not something that can be done out of the box unfortunately. I did a quick search on the internet and the VMware internal mailing lists but couldn’t find anything useful and that’s why I booted the ISO and logged into the console via “ALT-F1” -> Unsupported -> enter.

After some fiddling around in the ESXi iso I noticed a file called “/usr/lib/vmware/installer/ThinESXInstall.py”. I am not a python guru but I guess the following lines were pretty obvious:

Steps = [ WelcomeStep, LicenseStep, TargetSelectionStep, ConfirmStep, \
WriteStep, PostConfigStep, CompleteStep, RebootStep ]

This line describes the steps taken during the install. After I noticed these I did a quick search again on the filename and an article came up of my friend from down under, Stu aka Mr Vinternals. Stu describes which steps can be removed to decrease the amount of manual intervention:

Steps = [ TargetSelectionStep, WriteStep, PostConfigStep, RebootStep ]

Only the TargetSelectionStep requires input at the moment but that is also something that can be fixed. Look at the script “ThinESXInstallSteps.py”. There is a section that describes the disk selection, you can automate it by altering it and selecting a local disk with “IsLocal()”. That’s all I can say for now….

ESXi – lessons learned part 2

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New week, new lessons learned… You can find part 1 here.

When Jumbo Frames were introduced in ESX 3.5 a lot of people were interested but it wasn’t supported for the VMkernel which is were most people want to use it as it reduces CPU cycles used due to iSCSI/NFS traffic. When vSphere was released it was one of the things I noticed first. Full support for Jumbo Frames… however:

  • Jumbo frames are not supported for VMkernel networking interfaces in ESXi. (page 54)

Although obvious in my opinion it wasn’t obvious for one of my customers:

  • VMware ESXi does not support web access at this time.

Although I personally usually disable web access as it a security risk this customer had specific operational procedures around vCenter failures which included web access. It’s not a huge problem as the vSphere/vCenter Client can directly connect to an ESXi host, but it is something you will need to keep in mind when implementing ESXi.

Another thing I discovered today is that scripted/unattended installations of ESXi are not currently supported which makes deploying difficult. (Not only unsupported but also not easily set up) I am currently investigating the option to at least install it with default settings and without manual intervention… If I am successful I will post it in the next “lessons learned”.

REVISED!