VMware just released several new patches of which security and critical patches. You can find the KB articles which describe the fixes here:
ESX:
ESXi:
esxi
esxtop values/thresholds!
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Limit your Cluster Size to 8?
Lately I have been seeing more and more people recommending to limit clusters to eight hosts. I guess I might be more or less responsible for this “myth“, unintentionally of course as I would never make a recommendation like that.
My article was based on the maximum amount of VMs per host in a HA cluster with 9 hosts or more. The current limit is 40 VMs per host when there are 9 hosts or more in a cluster. With a maximum of 1280 VMs per cluster. (32 hosts x 40 VMs)
So why this post? I want to stress that you don’t need to limit your cluster based on these “limitations”. Just think about it for a second, how many environments do you know where they have 40+ VMs running on every single host? I don’t know many environments where they do exceed these limits, I guess exceptions are VDI environments…
So why would you want to “risk” exceeding these limits? Simple answer: TCO. Having two clusters is more expensive than a single a cluster. For those who don’t understand what I am trying to say: N+1. In the case of a single cluster you will have 1 spare host. In the case of two clusters you will have two spare hosts in total.
Another justification for a single cluster is DRS. More hosts in a cluster leads to more opportunities for DRS to balance the cluster. A positive “side effect” is also that the chances of resource congestion are reduced because there are more VM placement combinations possible.
Is there a recommendation? What is the VMware Best Practice? There simply isn’t one that dictates the cluster size. Although the maximums should be taken into consideration for support you should calculate your cluster size based on customer requirements and not on a max config sheet.
ESXi – lessons learned part 3
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 2 revised
I mentioned in ESXi Lessons Learned 2 that Jumbo Frames were not supported for the VMkernel. It seems that it’s a mistake in the ESXi Config Guide as mentioned in this blog article on the VMware ESXi Chronicles Blog. Charu already contacted me about it but we needed to wait to update you guys before we received the definitive green light.
Charu Chaubal:
I am happy to say that this is merely an error in the documentation. In fact, ESXi 4.0 DOES support Jumbo Frames on VMkernel networking interfaces. The correction will hopefully appear in a new release of the documentation, but in the meantime, go ahead and configure Jumbo frames for your ESXi 4.0 hosts.