Glossary
This is the Advanced Message Queuing Protocol (AMQP) is an open standard application layer protocol for message-oriented middleware. The protocol has features such as messaging, queuing, routing both point-to-point and publish-and-subscribe, in addition to reliability and security.
Ballooning is the name given to the memory reclamation process invoked by the balloon driver. The balloon driver, also known as the vmmemctl driver, collaborates with the server to reclaim pages that are considered least valuable by the guest operating system. It essentially acts like a native program in the operating system that requires more and more memory. The driver uses a proprietary ballooning technique that provides predictable performance that closely matches the behavior of a native system under similar memory constraints. This technique effectively increases or decreases memory pressure on the guest operating system, causing the guest to invoke its own native memory management algorithms. You can refer to the following vSphere memory management paper for additional details: http://www.vmware.com/files/pdf/perf-vsphere-memory_management.pdf
This is where you are allocating more virtual CPU resources than what is physically available on the ESX Host, for further reading refer to vSphere Best Practices Paper: http://www.vmware.com/pdf/Perf_Best_Practices_vSphere4.0.pdf
vSphere Distributed Resource Scheduler and vSphere DRS continuously balances computing capacity in resource pools to deliver the performance, scalability and availability not possible with physical infrastructure. DRS uses VMotion to move VMs around in order to more fairly distribute workloads.
This is the either Linux or Windows based operating systems that are installed on the Virtual Machine.
A Host in VMware terminology is a Server Hardware that is running VMware’s ESX bare metal hypervisor. It is a “host” for Virtual Machines to run on.
This is where you have allocated more RAM than is physically available on the host
The minimum amount of physical memory guaranteed to be made available to the VM at all times. If this requested reserved memory is not available upon VM startup, the Vm will simply not start. A successful startup of the VM means the required memory was reserved.
Dependency injection is a specific form of inversion of control where the concern being inverted is the process of obtaining the needed dependency. The term was first coined by Martin Fowler to describe the mechanism more clearly. Dependency injection in object-oriented programming is a technique that is used to supply an external dependency or reference, to a software component. In technical terms, it is a design pattern that separates behavior from dependency resolution, thus decoupling highly dependent components. Instead of components having to request dependencies, they are given, or injected, into the component.
In software engineering, Inversion of Control (IoC) is an abstract principle describing an aspect of some software architecture designs in which the flow of control of a system is inverted in comparison to procedural programming. In traditional programming the flow of the business logic is controlled by a central piece of code, which calls reusable subroutines that perform specific functions. Using Inversion of Control this “central control” design principle is abandoned. The caller’s code deals with the program’s execution order, but the business knowledge is encapsulated by the called subroutines.
In practice, Inversion of Control is a style of software construction where reusable generic code controls the execution of problem-specific code. It carries the strong connotation that the reusable code and the problem-specific code are developed independently, which often results in a single integrated application.
In addition to the usual 4KB memory pages, ESX also makes 2MB memory pages available (commonly referred to as “large pages”). By default ESX assigns these 2MB machine memory pages to guest operating systems that request them, giving the guest operating system the full advantage of using large pages. The use of large pages results in reduced memory management overhead and can therefore increase hypervisor performance. If an operating system or application can benefit from large pages on a native system, that operating system or application can potentially achieve a similar performance improvement on a virtual machine backed with 2MB machine memory pages. Consult the documentation for your operating system and application to determine how to configure them each to use large memory pages. More information about large page support can be found in the performance study entitled Large Page Performance (available at http://www.vmware.com/resources/techresources/1039)
Non-Uniform Memory Access (NUMA) is a computer memory design used in multiprocessors, where the memory access time depends on the memory location relative to a processor. Under NUMA, a processor can access its own local memory faster than non-local memory, that is, memory local to another processor or memory shared between processors.
A vApp is a collection of virtual machines (and potentially other vApp containers) that are operated and monitored as a unit. From a management perspective, a multi-tiered vApp acts a lot like a virtual machine object. It has power operations, networks, datastores, and its resource usage can be configured.
A virtual machine is a software implementation of a machine, i.e. computer that executes programs like a physical machine would. VMs can be created with variant compute resources, such as Virtual CPU, referred to as vCPU, RAM, and Storage.
vMotion technology, deployed in production by 80% of VMware customers leverage the complete virtualization of servers, storage, and networking to move an entire running virtual machine instantaneously from one server to another. vMotion uses the VMware cluster file system to control access to a virtual machine’s storage. During a vMotion, the active memory and precise execution state of a virtual machine is rapidly transmitted over a high speed network from one physical server to another, and access to the virtual machines disk storage is instantly switched to the new physical host. Since the network is also virtualized by the VMware host, the virtual machine retains its network identity and connections, ensuring a seamless migration process.
VMware vCenter Server is the simplest, most efficient way to manage VMware vSphere—whether you have ten VMs or tens of thousands of VMs. It provides unified management of all the hosts and VMs in your datacenter from a single console with an aggregate performance monitoring of clusters, hosts and VMs. VMware vCenter Server gives administrators deep insight into the status and configuration of clusters, hosts, VMs, storage, the guest OS and other critical components of a virtual infrastructure—all from one place.
Like its predecessor ESX, ESXi is a “bare-metal” hypervisor, meaning it installs directly on top of the physical server and partitions it into multiple virtual machines that can run simultaneously, sharing the physical resources of the underlying server. VMware introduced ESXi in 2007 to deliver industry-leading performance and scalability while setting a new bar for reliability, security and hypervisor management efficiency.
While both architectures use the same kernel to deliver virtualization capabilities, the ESX architecture also contains a Linux operating system (OS), called “Service Console,” that is used to perform local management tasks such as executing scripts or installing third party agents. The Service Console has been removed from ESXi, drastically reducing the hypervisor code-base footprint (less than 150MB vs. ESX’s 2GB) and completing the ongoing trend of migrating management functionality from the local command line interface to remote management tools.
VMware vSphere, (prior name, VMware Infrastructure 4) is VMware’s first cloud operating system, able to manage large pools of virtualized computing infrastructure, including software and hardware.