Showing posts from March, 2017

Checking Distributed Switch PNICs for Invalid VLAN Traffic

4/26/17 Update: I changed this script so that it no longer uses the min/max VLAN numbers and instead discovers a list of valid VLANs based on the Port Groups that are defined on the VDS.  It then alerts if it sees any VLANs that are not in that list.

One of my customers has several physical uplinks going into their ESXi hosts, each carrying different sets of VLANs.  They recently had an issue where an uplink with one set of VLANs was accidentally attached to a VDS that was configured for the other set of VLANs.  This wasn't a catastrophic issue, as the VDS didn't have port groups defined for those invalid VLANs and so any traffic was dropped into the bit bucket, but it did mean that 1 of the links going into that switch was useless.

After we corrected the issue, we decided that we should audit the environment to see if this problem had occurred anywhere else but not been detected.  We decided that the best way to perform an initial scan of the environment would be to leverage …

Getting VM EVC Mode Requirements via PowerCLI

One of my customers was preparing to do some major ESXi host reconfiguration and so needed to shift VM workload from one cluster to another.  They had a challenge in that their clusters were running with different EVC modes, and they wanted to move VMs from the newer cluster to the older cluster.  "Impossible!" the strawman says, "it can't be done!"

Well, yes and no.  That's absolutely correct that you can't vMotion a VM that powered up on an Ivy Bridge CPU back onto an ESXi host with a Sandy Bridge processor.  The reason for this is that the VM, during its power on operation, scans the CPU of its host for a list of CPU features that are available and begins potentially using those features, which means that it can't be moved to a processor that doesn't have those features.  The VM, in effect, inherits its host's EVC Mode for the lifespan of this power cycle.  Until the VM goes through a complete new power cycle (not a reboot from within the…