1. A method for caching I/O data in a solid state drive (SSD) locally attached to a host computer supporting the running of a virtual machine (VM), the method comprising: allocating portions of the SSD to use as cache storage for VMs running on the host computer; maintaining a mapping relationship between unique identifiers for VMs running on the host computer and one or more process identifiers (PIDs) associated with processes running in the host computer that correspond to each of the VM's execution on the host computer; receiving an I/O request, wherein the I/O request is intended for a virtual disk file of the VM that is remotely stored from the host computer; determining a PID associated with I/O request; extracting a unique identifier for the VM from the mapping relationship based on the determined PID; and accessing a portion of the SSD corresponding to the unique identifier of the VM that is used as a cache for the VM in order to handle the I/O request.