iSCSI is a protocol that allows for the transmission and use of SCSI commands and features over a TCP- based network. iSCSI allows systems to use block-level storage that looks and behaves as a SAN would with physical servers, but to leverage the TCP network within a virtualized environment and cloud.

Portability is the ease with which a service or application can be moved between different cloud providers.
Maintaining portability gives an organization great flexibility between cloud providers and the ability to shop for better deals or offerings.

Explanation
Representational State Transfer (REST) is a software architectural scheme that applies the components, connectors, and data conduits for many web applications used on the Internet. It uses and relies on the HTTP protocol and supports a variety of data formats.

A Type 2 hypervisor differs from a Type 1 hypervisor in that it runs on top of another operating system rather than directly tied into the underlying hardware of the virtual host servers. With this type of implementation, additional security and architecture concerns come into play because the interaction between the operating system and the hypervisor becomes a critical link. The hypervisor no longer has direct interaction and control over the underlying hardware, which means that some performance will be lost due to the operating system in the middle needing its own resources, patching requirements, and operational oversight.