As I posted earlier, I have upgraded my lab from VMware vSphere 4.1 to VMware vSphere 5.0; during this upgrade (clean installation in some parts) I added 3rd NICs to hosts and created two vSwitch with one VMKernel for management and storage connection (multipathing) and one dvSwitch for some special VMs and features (FT Logging and vMotion). For some tests I changed configuration 0f VMKernel which connected to the dvSwitch for vMotion. ❓
I planned some upgrade on one of these hosts so tried to migrate VMs to the other host and placing it in the “Maintenance Mode”, just after my first try, I get an error and migration failed when the process was just about 9 percent; 🙁 the screenshot of the error is posted below.
I searched for “Migration to host <> failed with error Already disconnected (195887150).” and found “KB1030267“.
In this KB, it’s recommended to checking network health using three steps, so I did it while I was sure that I enabled “Jumbo Frames” in the past and the firewall was checked in the time of first installation. 🙄
I looked into the network configuration (Distributed Switch) for gathering some basic information about current state and IP settings.
While I was looked into the page, I pressed blue “i” sign (information button) next to the “vmk2” for checking jumbo frames setting and after that the uplink information.
As it’s shown in the above screen shots, the “MTU (Maximum Transmission Unit)” in the VMKernel and dvSwitch is different; I opened the “dvSwitch Settings” window and changed the MTU to 9000.
Waited some times for the changes applied to the both hosts and then tried again for migrating same VM and it finished successfully.
This KB get the right “Resolution” but let me add some notes to it (mainly as reminder) in order to make it more clear; if the “Jumbo Frames” sets on the VMKernel for vMotion in one host, all other hosts should have same MTU as well as connected vSwitches/dvSwitches. Connected vSwitches/dvSwitches should have same or grater MTU so they would let the data exit the host in the first step. 😉