Not long ago I wanted to vMotion a virtual machine, it failed with a general system error at 80%. First thing that crossed my mind was, it must have a CD/DVD device attached. Wich is usually the reason for failing vMotion. So I editted the virtual machine settings from “client device” to “host device” and back. Checked to make sure there were no VMware tools upgrades that got stuck and tried it again. Still, I got the same error. I vMotionned some other machine off the same host, just to make sure vMotion was still viable. That worked, so vMotion on the cluster was still functional. It had to be something else related to this particular virtual machine.

I checked all it’s settings, but didn’t notice anything unusual. I then checked the vmx log files of the virtual machine and the hostd log files, to see if I could find anything out of the ordinary in the logs. Among other things I found these entrances in the logs, wich struck me as odd:

Vmon_MigrateWriteGotData: Limit Exceeded
MigrateWrite failed
Could be an instance of a bug 49917

When I Googled for “migration write data limit exceeded” I found this VMware KB, VMware KB1011971. It states that this issue may occur on ESX(i) clusters earlier than 4.0 update 1, when the Video RAM of a virtual machine is greater than 30 MB. Since this machine was running on one of our (soon to be extinct) ESX 3.5 clusters, I gathered this might be it. I checked the virtual machine settings again. This time for the Video RAM settings and it turned out the machine had 32 MB of Video RAM. After checking with the client, I brought the VM down, editted it’s Video RAM and brought it back online. This time it vMotionned without any problem.

Once again, one of life’s little annoyances resolved.