When vMotioning a VM (specifically the .vswp file) residing on an NFS datastore you may see the following error.

vMotion fails with the error: remote host IP_Address failed with status Busy

This issue originally occurred in vSphere 4.1 but appears to have reappeared in vSphere 5.5 Update 2.

Luckily there is a workaround for now, until VMware can investigate and resolve the problem.

The workaround is to modify the advanced setting “Migrate.VMotionResolveSwapType” from the default of 1, to 0 on both the source and destination hosts. If you want to solve this for your entire cluster, then every host needs to be modified.

To modify the setting:

Launch the vSphere Client and log in to your vCenter Server. Select the source ESX host and then click the Configuration tab. Click Software > Advanced Settings > Migrate. Under the Migrate options, locate the line containing Migrate.VMotionResolveSwapType. By default, it is set to 1. Change the value to 0. Click OK. Repeat Steps 2 to 6 for all hosts in the cluster.

The official VMware KB is below.