Techniques for using a cache to accelerate virtual machine (VM) I/O are provided. In one embodiment, a host system can intercept an I/O request from a VM running on the host system, where the I/O request is directed to a virtual disk residing on a shared storage device. The host system can then process the I/O request by accessing a cache that resides on one or more cache devices directly attached to the host system, where the accessing of the cache is transparent to the VM.