Wang et al, [26] proposed XenPR, a process recovery mechanism based on Xen. Similar to Otherworld and ALDR,XenPR also uses a small kernel image that takes control when a crash occurs. However, XenPR relies on saving the process state using files, which are used later to restore the processes to their pre-crash states. This is similar to the checkpoint/restart technique. XenPR currently does not handle a large number of process types (e.g., processes with open sockets and processes that use IPC mechanisms). The approach also incurs overhead because of the need to start the small kernel and save the state into files. In contrast, ALDR does not need to do any state saving into files, as ALDR directly accesses in memory the state of the entire crashed-OS instance with the help of the hypervisor. Also, because ALDR resurrection does not require a full LPAR(Logical PARtition) initialization and OS re-IPL (Initial Program Load), the whole process is very fast.