Hello,
if you want to add a new vdisk (vmdk file) to a running virtual machine, you can do it via command line.
First, connect to the esxi host where is the placed the vm that you want to add a new vdisk/vmdk.
Then go to the datastore where you want to place the new vdisk/vmdk:
cd /vmfs/volumes/WhatEverDatastore/
Then create the vmdk file using vmkfstools:
vmkfstools -c 150G --diskformat zeroedthick vDisk.vmdk
Finally, add the new vdisk to the virtual machine:
First, get the vmid of the virtual machine:
vim-cmd vmsvc/getallvms
With the vmid, add the vdisk/vmdk:
vim-cmd vmsvc/device.diskaddexisting 464 /vmfs/volumes/WhatEverDatastore/vDisk.vmdk 0 3
Best regards,
Pablo
P.D: If you want a linux virtual machine be able to detect the new vDisk, check this.