vCenter Server

vCenter Server – Management Layer:  vCenter Server 5.0 comes under the management layer of vSphere 5.0. The vCenter Server provides a convenient single point of control to the datacenter. It runs on top of a Windows 64-bit operating system to provide many essential datacenter services, such as access control, performance monitoring, and configuration.

It is a single Windows service and is installed to run automatically. As a Windows service, vCenter Server runs continuously in the background. It monitors and manages the ESXi hosts and virtual machines, even when no vSphere Clients are connected or users are logged onto the computer where it resides.

It runs on the top of Windows 2003 and 2008 Server 64-bit versions

 It unifies the resources from the individual computing servers to be shared among virtual machines in the entire datacenter. It accomplishes this by managing the assignment virtual machines to the computing servers and the assignment of resources to the virtual machine within a given computing server based on the policies set by the system administrator.

A low-cost alternative to the vCenter Server Windows implementation is available in the form of vCenter Server appliance, which is a vCenter Server implementation running on a pre-configured Linux-based appliance.

vCenter Server Appliance is supported only on ESX or ESXi 4.0 and 4.1 and ESXi 5.0. It requires at least 7GB of disk space and is limited to a maximum size of 80GB.

vCenter Server Appliance supports Oracle, DB2, and embedded databases within vCenter Server Appliance.However, Microsoft SQL Server is not supported

To deploy vCenter Server Appliance, you must download the .VMDK and .OVF files from VMware Web site to your system. Ensure that you save the .VMDK and .OVF files in the same folder.

You can log in to vCenter Server Appliance to access the vCenter Server appliance configuration settings

The format of the address is http://(vCenter server virtual appliance IP address):5480.

The Login page of the vCenter Server Appliance is displayed.

If you are logging in for the first time, then the default username and password would be root and vmware

By going to the Authentication tab, in the vCenter Server Appliance, you can configure the authentication settings. The vCenter Server Appliance can be configured to authenticate against a NIS or Active Directory server.

vCenter Server 5.0 provides a selection of interfaces for datacenter management and virtual machine access. Users can choose the interface that best meets their needs, such as vSphere Client 5.0, vSphere Web Client, or terminal services such as Windows Terminal Services or Xterm.

The vCenter Server components include User Access Control, Core Services, Distributed Services, vCenter Server Plugins, and vCenter Server Interfaces.

- The User Access Control component    allows the system administrator to   create and manage different levels of access to vCenter Server for different classes of users.- Core Services are basic management services for a virtual datacenter.

A vCenter vApp has functions similar to a virtual machine. It can contain one or more virtual machines and appliances.

Another core service, vServices, enables you to use the platform for running add-on vCenter management and security applications, in addition running virtual machines. vServices packages and manages those applications.

- Distributed Services are solutions    that extend vSphere capabilities    beyond a single physical server. vMotion, Storage vMotion, DRS, DPM,   VMware HA, and FT are distributed    services that enable efficient and automated resource management and high availability for virtual machines.

They enable fine-grain, policy-driven resource allocation, and high availability of the entire virtual datacenter. Distributed Services allow the configuration and management of these solutions centrally from vCenter Server.

- vCenter Server Plugins extend the capabilities of vCenter Server by providing more features and functions. Plugins are applications that you can install on top of vCenter Server 5.0.

Plugins such as vCenter Storage Monitoring, vCenter Hardware Status, and vCenter Service Status are installed as part of the base vCenter Server product. Other plugins such as vSphere Update Manager, vShield Zones, and Data Recovery are packaged separately and need to be installed separately.

Plugins introduced in vCenter Server 5.0 are: Auto Deploy, Authentication Proxy, Network Core Dump, vSphere Syslog Collector.

The VMware vSphere Update Manager enables centralized management for vSphere 5.0 and offers support for VMware ESX/ESXi hosts, virtual machines, and virtual appliances. With Update Manager, you can Upgrade and patch ESX/ESXi hosts.

- Install and update third-party software on hosts.

- Upgrade virtual machine hardware, VMware Tools, and virtual appliances.

- vCenter Server Interfaces integrate vCenter Server with third party products and applications.

vCenter Server’s core services include several basic management services for a virtual datacenter:

- Resources and VM Inventory Management Service organizes ESXi hosts, virtual machines, and    resources in the virtual environment and facilitates their management.

- Task Scheduler Service schedules actions such as vMotion to happen at a given time.

- Statistics and Logging Service logs  and reports on the performance and resource utilization statistics of    datacenter elements, such as virtual machines and hosts.

- Alarms and Event Management Service tracks and warns users on potential resource over-utilization    or event conditions.

- Virtual Machine Provisioning Service guides and automates the provisioning of ESXi hosts and virtual machines.

- Host and Virtual Machine Configuration Service allows the configuration of hosts and virtual machines.

Optional vCenter Server components. These include vMotion, Storage vMotion, Storage Distributed Resource Scheduler or DRS, VMware vSphere High Availability or HA, vSphere Fault Tolerance, and vSphere Distributed Power Management or DPM. The optional distributed services extend vSphere’s capabilities to the next level. They enable fine-grained, policy-driven resource allocation, high availability, and networking of the entire virtual datacenter. The distributed services also enable the configuration and management of these solutions centrally from vCenter Server. Additionally, these distributed services enable an IT organization to establish and meet its production Service Level Agreements with its customers in a cost-effective manner.

The database interface connects to Oracle, Microsoft SQL Server, or IBM DB2 to store information, such as host configurations, resources and inventory for ESXi hosts and virtual machines, performance statistics, events, alarms, user permissions, and roles.

Microsoft SQL Server 2008 R2 Express is bundled with vCenter Server and is used for small deployments containing upto 5 hosts and 50 virtual machines.

The vSphere API connects with third-party solutions and VMware management clients. The vSphere 5.0 API is public and therefore available for custom application development. Using one API for both third-party applications and ESXi host communication reduces the need to maintain two APIs and assures that the API upon which custom applications are based will always be up-to-date.

The Active Directory interface connects to Active Directory to obtain user access control information. User Access Control allows the system administrator to create and manage different levels of access to the vCenter Server for different users

vCenter Server/ESXI Communication When you first add a host to vCenter Server, the vCenter Server sends a vCenter Server agent to run on the host.The vCenter Server agent acts as a small vCenter Server to perform several functions, such as

- Relay and enforce resource allocation decisions made in vCenter Server, including those that the DRS engine sends.

- Pass virtual machine provisioning and configuration change commands to the host agent.

- Pass host configuration change commands to the host agent.

- Collect performance statistics, alarms, and error conditions from the host agent and send them to the vCenter Server.

- Allow management of ESXi hosts at different release versions.

Virtual Infrastructure Interface Layer: You can access a vSphere datacenter through the vSphere Client, through a Web browser with vSphere Web Client, through a command-line interface, or through terminal services such as Windows Terminal Services.

The vSphere Client is a required component and the primary interface for creating, managing, and monitoring the ESXi host, virtual machines, and their resources. It also provides console access to virtual machines. The vSphere Client is installed on a Windows machine with network access to the ESXi host or the vCenter Server system. Depending upon whether the vSphere Client connects to the ESXi host or vCenter Server system, the interface displays slightly different options. While all the management activities are performed by vCenter Server, you must use the vSphere Client to monitor, manage, and control the server. An administrator can login to a single vSphere Client to manage multiple vCenter Servers or ESXi hosts. This is made possible through a technique called vCenter Linked Mode.

If you log into one vSphere Client, it automatically logs into all vCenter Server instances for which you have valid credentials and provides visibility to the entire inventory. One can now easily navigate across multiple datacenters and take action from the same console.

You cannot migrate hosts or virtual machines between the vCenter Server systems connected in Linked Mode.

vCenter Linked Mode uses Microsoft Active Directory Application Mode or ADAM to store and synchronize data across multiple vCenter Server instances. ADAM is an implementation of Lightweight Directory Access Protocol or LDAP. ADAM is installed automatically as part of vCenter Server installation. Each ADAM instance stores data from all the vCenter Server systems in the group. This information is regularly replicated across all the ADAM instances in the connected group to keep them in sync.

The vSphere Web Client is a browser-based interface for configuring and administering virtual machines. It enables you to connect to a vCenter Server system to manage an ESXi host through a browser.

It is a browser-based, fully-extensible, platform-independent implementation of vSphere Client based on Adobe Flex.

It can perform virtual machine deployment and some monitoring functions only. You cannot use this client to configure hosts, clusters, networks, datastores, or datastore clusters.

The vSphere includes command-line tools such as vSphere PowerCLI and vSphere CLI (vCLI) for provisioning, managing, and monitoring hosts and virtual machines. vSphere SDKs provide standard interfaces for VMware and third-party solutions to access vSphere.

Terminal services such as Windows Terminal Services or Xterm provide direct access to virtual machine consoles. Accessing ESXi hosts directly should be done only by physical host administrators in special circumstances.

A host profile captures the configuration of a specific host. This profile can then be used to configure other hosts or validate if a host’s configuration meets the requirements set by the administrator. This greatly reduces the manual steps involved in configuring hosts and maintaining consistency and correctness in host configuration across the datacenter.

Host profiles have been enhanced in vSphere 5.0 to provide support for stateless ESXi. A stateless ESXi host has no static data on a local disk; all information is held in memory. Such a host is just a server appliance and can be easily swapped out if broken.

Orchestrator or vCO is an automation and orchestration platform that provides a library of extensible workflows. It enables vSphere administrators to create and execute automated, configurable processes to manage their VMware virtual environment. Orchestrator provides drag-and-drop automation and orchestration for the VMware virtual environment.

Difference between automation and orchestration, Automation provides a way to perform frequently repeated processes without manual intervention. For example, a shell, Perl, or PowerShell script that adds ESXi hosts to vCenter Server.

On the other hand, orchestration provides a way to manage multiple automated processes across heterogeneous systems. An example of this would be to add ESXi hosts from a list to vCenter Server, update a CMDB with the newly added ESXi hosts, and then send email notification.

Orchestrator provides several benefits. It helps vSphere administrators ensure consistency and standardization and achieve overall compliance with existing IT policies. It also shortens the time for deployment of a complex environment (for example, SAP) to hours instead of days.

Orchestrator also enables vSphere administrators to react faster to unplanned issues in VMware datacenter. For example, when a virtual machine is powered off unexpectedly, the vSphere administrator can configure options to trigger the “Power-On” workflow to bring the virtual machine back online.

Orchestrator is silently installed by the vCenter Server installer as an additional component. Please

refer to the VMware vCenter Orchestrator Administration Guide for details on prerequisites and installation steps.

To access vCenter Orchestrator Configuration, the VMware vCenter Orchestrator Configuration service should be running.

To access the vCenter Orchestrator Configuration interface, type http://(appliance_name_or_IP_address):8282 in the Web browser address bar and log in with default credentials. 8282 is the access port reserved for the Web UI of vCenter Orchestrator Configuration.

A workflow combines actions, decisions, and results that, when performed in a particular order, complete a specific task or process in a virtualized infrastructure. Workflows take inputs according to their function. vSphere administrators can create workflows that execute according to defined schedules, or that execute if certain anticipated events occur. Inputs can be provided by vSphere administrators, by other users, by another workflow or action, or by an external process such as a Web service application. Workflows perform some validation and filtering of inputs prior to execution.

vApp : You can use VMware vSphere as a platform for running multi-tier applications, in addition to running virtual machines. These applications can be packaged to run directly on top of vSphere. This format of packaging and managing applications is called vApp.

vApps are packaged as Open Virtual Machine Format or OVF files. This format enables exchange of virtual appliances across products and platforms and offers several advantages. The first advantage is that OVF files are compressed, which enables faster downloads. Additionally, vCenter Server validates an OVF file before importing it and ensures that it is compatible with the intended destination server. OVF files also provide for rich metadata. This enables you to describe important characteristics such as the vApp anatomy, its relationship to other virtual machines, and resource and availability requirements.

You can use vCenter Server to create, package, and publish a vApp. Alternatively, independent software vendors can develop and package vApps and publish them to the Virtual Appliance Marketplace for deployment in vSphere

Alarms: Alarms are notifications that are set on events or conditions for an object. For example, the vCenter Server administrator can configure an alarm on disk usage percentage, to be notified when the amount of disk space used by a datastore reaches a certain level.

Events: Events are the records of user actions or system actions that occur on objects in vCenter Server or on a host. Event data includes details about the event, such as who generated it, when it occurred,

and what type of event it is.

Performance Charts: Performance charts graphically represent statistical data for various devices and entities managed by vCenter Server. They display data for a variety of metrics, including CPU, disk, memory, and network usage.

VMware Tools includes the Perfmon DLL that enables vSphere administrators to monitor key host statistics from inside a virtual machine running a Windows operating system.

Resource Maps: vSphere administrators use resource maps to monitor proper connectivity which is vital for migration operations, such as VMware vSphere vMotion or vSphere Storage vMotion. Resource maps are also useful to verify VMware vSphere High Availability, VMware Distributed Resource Scheduler or DRS cluster memberships, and resource connectivity.

References and further reading
http://pubs.vmware.com/vsphere-50/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-50-host-management-guide.pdf