Resizing Partitions in a virtualized environment
Thomas Hampel
12 January 2013Running lots of virtual machines on the same hypervisor is not a problem until reaching the point of running out of disk space for one virtual machine.
Its not a complex task to assign more disk space to an existing VM.
When using Redhat or CentOS, you can increase the file size on the fly. See this VMware knowledge base article.
for other operating systems LiveCDs like Gparted or Parted Magic will do the job.
Step by step instructions for using Gparted are available, e.g. here.