Before vSphere 6.5 it was impossible to increase the VMDK size of a DISK that was larger than 2TB when the Virtual Machine was powered on. That was a fact that not many organizations were aware of it until they stumbled upon it. There are three AC policies in vSphere 6.5: Slot policy; As policy name states it uses slot size to calculate an amount of available resources for a failed host scenario. The slot size can be either defined automatically by using the largest reservations for RAM and vCPU. Alternatively, you can define a custom slot size. Often referred to in the virtual community as the vSphere Resource kit, the Host Resource Deep Dive zooms in on hardware resources such as CPU and Memory and covers how the vSphere 6.5 resource scheduler manages these. The Clustering Deep Dive builds on top of that and zooms in how a group of ESXi hosts work together and provide clustering.
When vSphere 6.5 was announced I was quite impressed about the features. Gathering more and more hands-on experience so far I am more than happy with it.
One of the new features that can have a real operational benefit hasn't been documented so far that often (or at least I haven't seen it anywhere).
Vsphere 6.5 Slot Size Chart
Before vSphere 6.5 it was impossible to increase the VMDK size of a DISK that was larger than 2TB when the Virtual Machine was powered on. That was a fact that not many organizations were aware of it until they stumbled upon it.
From an architectural point of view there shouldn't be many use cases where such a large disk layout would be the best practice. But from an operational point of view for many of my customers this has been a bigger issue.
The good thing is: With vSphere 6.5 this is not the case anymore. Important: Hardware Version 13 (vHW 13) is not required for this to work – therefore just the vSphere platform and not the VM has to be upgraded.
Vsphere 6.5 Ha Slot Size
Increasing a hard disk from 2.4 to 3TB will just work while the VM is powered on.
Voila. The disk can be used within with the fully size without any service interruption. Quite cool isn't it?
Another quite useful enhancement within vSphere 6.5 is the fact that we can now see details about the hardware customization within the events. While in the pre vSphere 6.5 era we were only able to see that a configuration of the VM took place we see now more details about this VM configuration task.
Just select reconfiguration event in Host & Clusters or VMs & Templates: VM -> Monitor -> Events
The first bigger vSphere 6.5 update must be around the corner. So I would recommend you to plan the upgrade. Check out my blog post about the general design considerations and tasks to be done before upgrading the vCenter.
