, they also tend to be more flexible and provide better performance (11, n.d.). Object storage, also called object-based storage, is a generic term that describes an approach to addressing and manipulating discrete units of storage called objects. Like files, objects contain data-but unlike files, objects are not organized in a hierarchy. Every object exists at the same level in a flat address space called a storage pool and one object cannot be placed inside another object (12, n.d.). Both files and objects have metadata associated with the data they contain, but objects are characterized by their extended metadata. Each object is assigned a unique identifier, which allows a server or end user to retrieve the object without needing to know the physical loca- tion of the data. 4.2.2 VIRTUAL INFRASTRUCTURE MANAGER One of the most important and influential pieces of the NFVI is the VIM. The VIM is responsible for managing the virtualized infrastructure of an NFV-based solution. VIM operations include the following: 1. It keeps an inventory of the allocation of virtual resources to physical resources. This allows the VIM to orchestrate the allocation, upgrade, release, and reclamation of NFVI resources and optimize their use (13, n.d.). 2. It supports the management of VNF forwarding graphs by organizing virtual links, net- works, subnets, and ports. The VIM also manages security group policies to ensure access control (13, n.d.). 3. It manages a repository of NFVI hardware resources (compute, storage, and networking) and software resources (hypervisors), along with the discovery of the capabilities and fea- tures to optimize the use of such resources (13, n.d.). The VIM performs other functions as well-such as collecting performance and fault informa- tion via notifications; managing software images (add, delete, update, query, and copy). In sum- mary, the VIM is the management glue between hardware and software in the NFV world (13, n.d.). 4.2.3 VIM SOLUTIONS When choosing a VIM, the market provides three categori