Veeam vPower NFS is used when you perform an Instant Recovery from a Veeam backup file, and allows Veeam to present the compressed backup file as regular vmdk to your ESXi host. You may have missed the configuration setting during the installation, but on a couple of servers I look after it was installed on C:.
Now on a server with 100GB C: I generally run with 20-30% free diskspace, but considering the size of some of the VMs I look after it only takes a couple to be started via Instant Recovery before you have filled up your vPower NFS (and C:) with virtual swap files.
Here is how to change the vPower NFS path:
On the server below there is already an Instant Recovery running so the C: is already pretty short of space, but D:, E:, and G: have loads of free space. So we will move the vPower NFS path E:.
The vPower NFS path has now been changed to E:vPowerNFS.