Final answer:
Virtualization improves system security by isolating virtual machines and enabling rapid recovery from breaches. For load balancing and fault-tolerance, it allows workloads to be distributed and provides redundancy and scalability. VMware and Xen both abstract memory for virtual machines, but VMware uses full virtualization while Xen employs paravirtualization.
Step-by-step explanation:
How Virtualization Improves System Security
Virtualization can improve system security by isolating virtual machines from each other. If one virtual machine is compromised, the others remain unaffected because they operate in separate environments. Additionally, virtualization allows for the regular snapshotting of VMs, enabling rapid recovery from security breaches without impacting the entire system.
Virtualization for Load Balancing and Fault-Tolerance
Load balancing and fault tolerance can be improved through virtualization by distributing workloads across multiple virtual machines and ensuring that if one VM fails, others can take over without disrupting services. The two main conditions for these features are:
Redundancy - The presence of additional systems or components that can take over in case of a failure.
Scalability - The ability of the system to handle increased loads by adding resources without significant changes to the system architecture.
Memory Virtualization in VMware and Xen
A similarity between memory virtualization mechanisms used by VMware and Xen is that both provide an abstraction layer that allows multiple operating systems to believe they are using physical memory directly when in fact it is virtual memory. A difference lies in their approaches: VMware uses full virtualization, which may include binary translation for memory management, whereas Xen uses paravirtualization, which requires the guest OS to be aware of the virtualization for more efficient memory operations.