Added to Cisco IOS Software Release 12.3(14)T, the Exclusive Configuration Change Access feature ensures that only one administrator makes configuration changes to a Cisco IOS device at a given time. This feature helps eliminate the undesirable impact of simultaneous changes made to related configuration components. This feature is configured using the global configuration command configuration mode exclusive mode and operates in one of two modes: auto and manual. In auto-mode, the configuration automatically locks when an administrator issues the configure terminal EXEC command. In manual mode, the administrator uses the configure terminal lock command to lock the configuration when entering configuration mode.
This example illustrates the configuration of this feature for automatic configuration locking:
!
configuration mode exclusive auto
!
Reference Exclusive Configuration Change Access (Config Lock).

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Cisco Configuration Replace and Configuration Rollback

Beginning in Cisco IOS Software Release 12.3(7)T, the Configuration Replace and Configuration Rollback features allow for archiving of the Cisco IOS device configuration on the device. Stored manually or automatically, the configurations in this archive can be used in order to replace the current running configuration using the configure replace filename command. This is in contrast to the copy filename running-config command. The configure replace filename command replaces the running configuration as opposed to the merge performed by the copy command.
You are advised to enable this feature on all Cisco IOS devices in the network. Once enabled, an administrator can cause the current running configuration to be added to the archive by using the archive config privileged EXEC command. The archived configurations can be viewed using the show archive EXEC command.
This example illustrates the configuration of automatic configuration archiving. This example instructs the Cisco IOS device to store archived
configurations as files named archived-config-N on the disk0: file system, to maintain a maximum of 14 backups, and to archive once per day (1440 minutes) and when an administrator issues the write memory EXEC command.
!
archive
path disk0:archived-config
maximum 14
time-period 1440
write-memory
!
Although the configuration archive functionality can store up to 14 backup configurations, you are advised to consider the space requirements before using the maximum command.

Reference : http://www.cisco.com/en/US/docs/ios/12_3t/12_3t7/feature/guide/gtrollbk.html

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ITIL Introduction

ITIL is ITSM

IT Service Management

is a set of specialized organization  capabilities to provide values to the customer in terms of  services.

Service - is a meant of delivering values to the customers by facililating outcomes ,customer want to achieve without the ownership of specific costs and risks.


Capabilities - are set of functions and processes used to manage services. Capabilities are intangible assets of organization and can not be purchased, it must be developed and matured over time.


Processes - are set of coordinated activities combining and implementing resources and capabilities in order to produce an outcome and values to the customer.

Processes become strategic assets when they create competitive advantage and market differentiation.

Processes are

• measurable, 
• deliver specific result,
• deliver outcomes for customer , 
• respond to specific event.

Functions - a team or group of people and the tools they use to carry out the processes or activities.

Service Owner - is responsible for for continual improvement for the services under their care.
Process Owner - is accountable for the outputs of the nominated process.
Process Operators - is responsible for normal execution of process activities.
System Architect - is responsible for designing the technical infrastructure needed for the services.

Customer - has the authority to negotiate with it department for the provision of services.

For example - PIZZA - if want to eat pizza , there are two ways to get it - either you prepare it yourself and take the ownership of cost and risk involved in preparation or you take the services of Pizza Hut who are the one of the best pizza makers. Here in pizza hut , process is making pizza and delivering it to the customer , Cook is process owner , delivery manager is service owner , delivery boy is process operators , branch manager will be system architect.. and you are the customer.

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Data center classification

Tier Level	Requirements
1	Single non-redundant distribution path serving the IT equipment Non-redundant capacity components Basic site infrastructure guaranteeing 99.671% availability
2	Fulfills all Tier 1 requirements Redundant site infrastructure capacity components guaranteeing 99.741% availability
3	Fulfills all Tier 1 and Tier 2 requirements Multiple independent distribution paths serving the IT equipment All IT equipment must be dual-powered and fully compatible with the topology of a site's architecture Concurrently maintainable site infrastructure guaranteeing 99.982% availability
4	Fulfills all Tier 1, Tier 2 and Tier 3 requirements All cooling equipment is independently dual-powered, including chillers and heating, ventilating and air-conditioning (HVAC) systems Fault-tolerant site infrastructure with electrical power storage and distribution facilities guaranteeing 99.995% availability

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TIA - 942 design topolody

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Backbone and Horizontal Cabling

The backbone cabling within the data center provides the critical connections between the entrance room, MDA and HDA. The backbone cabling in many of today’s data centers supports 10 Gigabit transmission speeds for current and future applications. The horizontal cabling within the data center provides the connection between the HDA and EDA and SAN, including the optional ZDA.

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Entrance Room/Telecommunication Room (ER/TR)

The entrance room of the data center is the location for access provider equipment, demarcation points and interface with other campus locations. The TIA-942 standard recommends locating the entrance room outside of the computer room for security purposes.
The telecommunication room is connected to the data center MDA through backbone cabling. TRs are spaces for housing equipment, cable terminations and cross connects that serve office areas on specific floors. In addition to voice, data, and wireless systems, TRs can house equipment for life safety/fire systems, security, and building automation systems.

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Storage Area Network (SAN)

The SAN houses all data storage devices such as disk arrays, tape libraries and high-capacity optical disk libraries for applications like video surveillance. The use of a separate SAN eliminates the need to store data directly on servers, which provides better network capacity. Access to stored data must be fast, requiring high-speed connections from the Horizontal Distribution Area.

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Zone Distribution Area (ZDA)

The optional ZDA acts as a consolidation point within the horizontal cabling run between the Horizontal Distribution Area and Equipment Distribution Area. Per the standard, the ZDA cannot contain any cross connects or active equipment.

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Equipment Distribution Area

The EDA is where equipment cabinets and racks house the switches and servers and where the horizontal cabling from the HDA is terminated at patch panels. In the EDA, racks and cabinets should be arranged in a hot aisle/cold aisle configuration to encourage airflow and reduce heat. Belden offers a variety of products for the EDA, including our high-end freestanding enclosures that help provide airflow and cooling:

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Main Distribution Area - MDA

MDA is a centrally located area that houses the main cross-connect as well as core routers and switches for LAN and SAN infrastructures.The MDA may include a horizontal cross-connect for a nearby equipment distribution area.

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What is an IDC ???

IDC - > Internet Data Ceneter

A data center is a facility used to house computer systems and associated components, such as telecommunications and storage systems. It generally includes redundant or backup power supplies, redundant data communications connections, environmental controls (e.g., air conditioning, fire suppression) and security devices.

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