My preference it is use vendor customised ESXi images where possible. They include vendor specific drivers which may be required to utilise the hardware properly and ensure you’re getting consistency across your esxi fleet.
Unfortunately Dell have managed to introduce a frustrating admin headache into their customised images.
It seem they changed the names of some of their customised VIBs between releases but kept the same files within those VIBS which causes the upgrade process to bomb out.
The remediation for this issue is to either manually uninstall the VIBs via the command line before performing the upgrade or upgrade using the standard VMware files Neither option is very enticing. Uninstalling the VIBs is time consuming across multiple hosts. Using the stand VMware files means you may miss out on a Dell update.
The issue is described in a VMware KB article and on the Dell community site.
Came across a reddit post the other day pointing out a bug in Changed Block Tracking which warrants further investigation.
A basic explanation of the bug is that if a VM has CBT enabled and it’s capacity is subsequently expanded by 128GB or more (either via a one off expansion or multiple smaller expansions over time) then CBT can no longer be relied upon for accuracy. Any backup utilising CBT must be treated as suspect.
To remediate the issue you need to disable and then re-enable CBT on the VM.
As you would expect there is a VMware KB explaining the situation in more detail.
The most comprehensive coverage I have found it on the educationalcentre.co.uk blog.
A recent post on the VMware Security & Compliance Blog announces some changes coming to the Transparent Page Sharing (TPS) feature of vSphere.
1. TPS is going to be disabled by default in the next update to ESXi.
2. There will be additional options for enabling and adding security to TPS.
Given the introduction of large pages the effectiveness of TPS has been somewhat limited therefore the impact should be minimal to environments that do not over allocate memory. There is a VMware Knowledge Base article that explains this quite well.
In addition the issue has been blogged by Frank Denneman, Josh Odgers, Michael Webster and Duncan Epping among others.
Finally, I thought Duncan Epping‘s note on his post about Project Fork was interesting ‘he disabling of TPS will be overruled per VMFork group. So the parent and childs belonging to the same group will be able to leverage TPS and share pages. ,