What is hard disk and what is its purpose?

- HDD or Hard Disk Drive is for data storage. 

- It is used for storage and retrieval of the digital information or data that is stored on it. 

- The data is stored or retrieved by means of its discs that rotate rapidly. 

Hard Disk and its Purpose

 

- These discs are known as the platters and are coated with some sort of magnetic material. 

- The major characteristic as well as benefit of hard disk drives is that they retain the data even when the power supply is switched off. 

- From hard disk, the data can be read in a manner of random access. 

- This means that the storing and retrieval of the individual blocks of the data can be done either sequentially or in any order that the user may like. 

- A hard disk may consist of one or more than one of those rigid platters. 

- These rotating discs have magnetic heads that are located on an actuator arm that is continuously moving and reads and writes data on their surfaces. 

- IBM was the first to introduce the hard disk in the year of 1956. 

- Hard disk drives are the most dominant and the prominent secondary storage device for the computers since 1960s. 

- Since then, it has been continuously improved. 

- The HDD units are produced by more than 200 companies; among them most prominent developers are Toshiba, Seagate, Western digital etc. 

HDD’s primary characteristics are:

Ø  Capacity and

Ø  Performance

- The former is specified in terms of the unit prefixes. 

- In some systems, the capacity of the hard disk drive might be unavailable to the user since being used by the operating system and the file system and may have a possibility of occurrence of redundancy.

- The latter is specified in terms of the movements of the heads for a file i.e., the average access time in addition to the time taken for moving the file under the head i.e., the average latency and data rate. 

HDDs are available in two most common factors namely:

Ø  3.5 inch for desktop computers

Ø  2.5 inch for laptops

HDDs might be connected to the system by any of the following standard interface cables:

Ø  Serial ATA or SATA cable

Ø  USB cable

Ø  Serial attached SCSI or SAS cable

- In the year of 2012, flash memory emerged as a tough primary competitor for the hard disk drives. 

- These flash memories are some sort of solid state drives or SSDs. 

- However, the HDDs will still continue to dominate the secondary storage for its advantages such as price per unit of storage and recording capacity. 

- But there is a different scenario is the case of portable electronics.

- Here, the flash drives are considered to be more useful then rotating HDDs because here the durability and physical size of the drive has also to be considered more when compared to price and capacity.

HDD uses the magnetic recording technology where the data is recorded by magnetizing a thin film of material that is typically ferromagnetic on a disk. 

- The binary data bits are represented by the sequential change in the direction of the magnetization.

- An encoding scheme is used for encoding the user data. 

- An example of such encoding scheme run – length limited encoding. 

- It is these schemes that determine how the magnetic transitions would represent the data.

The latest HDD technologies are:

Ø  Shingled write

Ø  CPP/ MGR heads

Ø  Heat assisted magnetic recording

Ø  Bit – patterned recording

What is autonomic networking?

- The concept of autonomic networking follows directly from the automatic computing.

- The initiation of the autonomic computing was done by the IBM Corporation in the year of 2001.

- This concept has been brought in to the present world networking scenario in order to make the creation of self - managing networks possible. 

- Self managing networks are required for overcoming the complexity of the various networks (including internet) that is increasing at a very rapid pace. 

- This is also necessary for the further growth of the networks i.e., beyond the network size that we have today. 

- Autonomic networking is a means for the management of the network complexity. 

- In future, it is quite a possibility that routers could not be configured directly. - A point will come when it won’t be manageable by humans. 

- Autonomic networking will also minimize the manual intervention to a large extent plus it will also cut down the dependencies on the operator. 

- NMS intervention will also be reduced. 

- A fully – fledged autonomic network is expected to be capable of the following:

Ø  Self – configuration

Ø  Self – protection

Ø  Self – optimization

Ø  Self – healing

- In traditional networking systems, the amount of configuration, monitoring and reporting to be done is very large and amount of routing is very less. 

- In the autonomic networking systems, things are just the opposite i.e., there is less amount of intent, feedback and reporting and routing is more along with the other operations such as discovery and autonomic interactions. 

In autonomic networking, there are 3 characteristics of the administrator interface:

1. It is abstract
2. Light weight
3. Wide scope

- The increasing complexity of the network is viewed as a problem by most of the experts and that it might prove to be hindrance in its usability in the near future. 

- Number of PDAs, game consoles and smart phones is increasing day by day and these need an interconnection.

- Though such kind of pervasive computing adds features but it also increases the burden on the networking infrastructure that already exists since the number of tasks is so large that it is very difficult for humans to manage alone. - Another thing that adds to the problem is the cost of keeping a manual control on a number of devices in the infrastructure.

- Another important aspect is the price of manually controlling huge numbers

of vitally important devices of current network infrastructures.

- An analogy to autonomic nervous systems is the autonomic nervous system

or ANS. 

- This system regulates all the functions of the body and its various organs.

- Autonomic network systems bear a close resemblance to the ANS.

- Autonomic networking is all about adding more intelligence to the network.

- A number of complex operations are required to be carried out such as admission control, authentication, billing, shaping, routing, policing, QoS prioritizing and video encoding for providing simple services to the customer. 

There are a number of problems in the way of network as mentioned below:

1. The ever increasing size of the network.
2. The heterogeneous nature of the applications and devices.
3. Increase in the requirement of service quality.
4. Increase in the user expectations.
5. Ever changing requirements.
6. Changing context

- Pre – defined context is kept in while designing networks with the traditional approaches. 

- Whenever there is a change in the context, it leads to more time consuming manual tasks. 

- Algorithms used today do not have the ability of detecting context changes and interpreting the policies. 

- Such manual management causes more loss and outages in the revenue of the organization. 

- In autonomic networking, the system itself optimizes the goals. 

What are characteristics of autonomic system?

Autonomic systems bring both challenges as well as opportunities for the future networking. The increasing numbers of users have had a negative impact on the complexity of the networks; it has also increased by multiple folds. Autonomic systems provide a solution for this problem. 

Characteristics of Autonomic System

1. High intelligence: These systems have more intelligence incorporated in to them which lets them tackle this increasing complexity easily.
2. Business Goal: They are driven by the business goal that the quality of experience of the user must be high. Even with the changing environment, there goals remain the same. But there are changes that take place in the low – level configurations. For example, when a user switches over to a low bandwidth network, the bit rate of the video has to be reduced in order to satisfy the goals of the business.
3. Complex operations: All the operations carried out in an autonomic system are complex in nature even for the simplest of the services. For example, authentication, video encoding, billing, routing, shaping, QoS prioritizing, admission control.
4. High level objectives: The human operator just has to specify the high – level objectives and it is left to the system whether it chooses to optimize one or more of the goals. In order to achieve this, the system has to translate these objectives in to low – level configurations.
5. Adaptability: The system has the ability to adapt itself to the current environment.
6. Policy continuum: There are a number of perspectives to this as mentioned below:

Ø  Business view: Includes guidelines, processes and goals.

Ø  System view: The service should be independent of the technology as well as the device that is being used.

Ø  Network view: It should be specific to technology but independent of the device.

Ø  Device view: Both technology and device specific.

Ø  Instance view: Operation should be specific to an instance.

7. Elements: The elements of the network are assumed to be heterogeneous by the autonomic communication systems whereas in plain autonomic computing the elements are taken to be as the homogeneous.
8. Distributed: These systems work up on a distributed environment.
9. Complexity: The complexity in autonomic systems is more because of the complex autonomic loop that includes the following operations:

Ø  Interaction between the context  and the business goals

Ø  The MAPE (monitor, analyze, plan and execute) loop.

10. Reliability: In autonomic systems, the network has the authority to decide for itself focusing on high level objectives. Autonomic systems rely heavily up on artificial intelligence. However, there are issues associated with artificial intelligence like it becomes difficult to intervene in between when the things go wrong.It is quite difficult to know whether the system is doing the things it is supposed to do or not.

11. Scalability: This is another major characteristic of autonomic systems. It is required to keep track of the large amounts of knowledge and information. Autonomic systems have three tools to take care of this:

Ø Distributed ontologies

Ø Distributed large – scale reasoning

Ø Exchanging only the useful information

ØDistributing information among the different components of the autonomic network.

But in these cases, detection of the conflicts is a difficult task. For handling the various interactions taking place the various autonomic components efficient protocols are required. 

Currently two approaches have been suggested for developing the autonomic networking systems namely:

1. Evolutionary Approach: Incorporating the autonomic behavior in to the pre – existing infrastructure. This approach will consist of updates in increments till a fully autonomic system is developed. This approach is more likely to be adopted even though it requires a lot of patchwork.

2.  Clean slate approach: This approach is focused up on re – designing of the internet.

What are autonomic systems? What is the basic concept behind autonomic system?

In this article we shall discuss about the autonomic systems, but before moving on to that we shall see a brief discussion regarding the autonomic computing. 

About Autonomic Computing

- Distributed computing resources have the ability of self–management. 

- This kind of computing is called autonomic computing and such systems are called autonomic systems. 

- Because of their unique capabilities, these systems are able to adapt to the changes that are both predictable and unpredictable. 

- At the same time, these systems keep the intrinsic complexities hidden from the users as well as the operators. 

- The concept of autonomic computing was initiated by IBM in the year of 2001. - This was started in order to keep a curb on the growing complexity of the management of the computer systems and also to remove any complexity barriers that prove to be a hindrance in development.

About Autonomic Systems

- Autonomic systems have the power to make decisions of their own. 

- They do this because of the high level policies. 

- These systems automatically check and optimize their status and adapt to the conditions that have changed. 

- The frame work of these computing systems is constituted of various autonomic components that are continuously interacting with each other. 

- Following are used to model an autonomic component:

1. 2 main control loops namely the global and the local.
2. Sensors (required self – monitoring)
3. Effectors (required for self-adjustment)
4. Knowledge
5. Adapter or planner

- The number of computing devices is increasing by a great margin every year. - Not only this, each device’s complexity is also increasing. 

- At present highly skilled humans are responsible for managing such huge volume of complexity. 

- The problem here is that the number of such skilled personnel is not much and this has led to a rise in the labor costs.

- It is true that the speed and automation of the computing systems have revolutionized the way world runs but now there is a need for a system that is capable of maintaining these systems without any human intervention. 

- Complexity is a major problem of the today’s distributed computing systems particularly concerning their management. 

- Large scale computer networks are employed by the organizations and institutions for their computation and communication purposes. 

- These systems run diverse distributed applications that are capable of dealing with a number of tasks. 

- These networks are being pervaded by the growing mobile computing. 

- This means that the employees have to be contact with their organizations outside office through devices such as PDAs, mobile phones and laptops that connect through wireless technologies. 

- All these things add to the complexity of the overall network that cannot be managed by human operators alone. 

- There are 3 main disadvantages of manual operating:

1. Consumes more time
2. Expensive
3. Prone to errors

- Autonomic systems are a solution to such problems since they are self – adjustable and do not require human intervention. 

- The inspiration or the concept behind the autonomic systems is the autonomic nervous system found in humans.

- This self – manageable system controls all the bodily functions unconsciously. - In autonomic systems, the human operator just has to specify the high level goals and rules and policies that would guide the management. 

- There are 4 functional areas of an autonomic system:

1. Self–configuration: Responsible for the automatic configuration of the network components.
2. Self–healing: Responsible for the automatic detection and correction of the errors.
3. Self–optimization: Monitors and controls the resources automatically.
4. Self–protection: Identifies the attacks and provides protection against them.

- Below mentioned are some characteristics of the autonomic systems:

1. Automatic
2. Adaptive
3. aware

What is meant by Dynamic Virtual Private Network?

Dynamic virtual private network or DVPN is a network used for interconnecting various virtual application networks. 

- These networks reduce the need for manual configuration by a large percentage (almost by 93 %). 

- Dynamic virtual private networks help a great deal in the simplification of the wide area connectivity spread across a virtual application network.

- These networks have a great complexity when compared to the other networks.

- Further, they prove useful in establishing interconnections between various campuses, data centers, and offices and so on via IPsec VPN encryption. 

- The solution offered by the DVPNs is quite scalable, simple and secure. 

- The dynamic virtual private networks are highly automated and therefore provide a simple management solution. 

- A DVPN can scale up to 1000 – 3000 sites on a single router. 

- All these sites together constitute the domain of the DVPN. 

- So it is obvious that a very large network can be scaled via multiple DVPNs. 

- The best thing about these DVPNs is that they support all the WAN technologies and therefore can be implemented up on all.

- Furthermore, they offer flexibility in reducing the cost when compared to the lower cost broadband access.

- All the network operations are simplified since DVPN has automated VPN setup plus provisioning.

- DVPNs offer high resilience without adding to the complexity of the network. 

- Another characteristic feature of a dynamic virtual private network is its carrier agnostic connectivity.

- One solution to DVPN is offered by HP that has got the following features:

1. Full mesh or hub – spoke configuration
2. Encryption based up on IPsec standards.
3. The control plane and the data plane have been separated to ensure scalability.
4. Up to 30,000 clients are supportable by the VAM (VPN address management) server.
5. Offers zero touch configuration.

- Another solution is offered by the Juniper networks. 

- Juniper’s DVPN is more of a client-less solution and has been designed for ‘remote access’ IPsec VPN. 

- The delivery of the client to the end users is made dynamically from SRX. 

- The remote access is simplified by DVPN since it provides the users the facility to secure the IPsec VPN tunnels without any need for configuring the VPN settings on their systems. 

- This whole process comes in to when the users login to the server’s web site. - Juniper’s DVPN solution can be licensed to 5, 10, 25 or 50 concurrent users. 

- It supports windows xp and above versions (both 32 and 64 bit).

- However, there are certain limitations for this solution:

1. It requires an external RADIUS server for providing an IP address and for XAUTH.
2. Does not support shared IKE id.
3. Mandatory PFS (perfect forward secretary).
4. Requires custom IKE/ IPsec security proposals.
5. Only IKE – id supported is the FQDN.

- Configuration for DVPN is required only on the SRX gateway.

- Dynamic virtual private network is more of an intranet enabler whose purpose is to complement the regular services offered by the internet by adding more services as well as resources to it. 

- One major feature of these networks is that they have an excellent ability of loading balance on – the – fly allocation of the resources. 

- These networks are more popular in businesses since they offer more security by means of packet encryption protocols. 

- Self – modification is possible for the DVPNs and so they are able to recognize the added nodes without help from routers.

- Encryption and authentication are two technologies used by DVPNs for securing packing data and delivering across the networks. 

- Until the data reaches it destination it remains unpacked or encapsulated. 

- For reaching the remote networks tunneling is used. 

What is IBM Rational Method Composer product?

One the major products of IBM is the Rational Method Composer or RMC. 

About Rational Method Composer

- This product has proved to be quite reliable in increasing the effectiveness as well as the agility of the software system or application.

- It provides platform that is quite flexible for process management. 

- This IBM product is equipped with the most comprehensive tooling of the software industry. 

- It also comes with the richest process library so as to provide assistance to the companies in the implementation of the effective processes so that they can come up with many successful IT and software projects. 

Characteristics of Rational Method Composer

1. The rational method composer have some very new practices that will surely improve the performance of many of the leading process experience as well as expertise in the following areas:

Ø  Agile development

Ø  Governance and compliance

Ø  Requirements management

Ø  Quality management

Ø  Change management

Ø  Release management

2. It helps greatly in the identification of the improvements that are needed by the mapping practices. The improvements identified by the rational method composer can be adopted in increments and improved also as per the business objectives of the project.
3. The rational method composer offers a choice of over 100 process guidance that are both select-able and customizable and are inclusive of the IBM rational unified process. This guidance can help you in solving common management, business and development problems. 
4. The facility of providing the corrective action and measured results is what makes the rational method composer more user friendly. Such measure let you harness the effectiveness of the practice adoption.
5. With Rational Method Composer you get the privileges for managing, authoring, measuring, evolving as well as deploying the effective processes that are tailor made for your software system or application project needs since it is the leading the eclipse – based tool of the software industry.
6. The rational method composer maintains consistency in driving the results across the whole project with the help of the best practices which have been proven and have been integrated with the following:

Ø  Measurements

Ø  Agile

Ø  Reporting

Ø  Project management tools and

Ø  Services

7. A quantum leap forward is represented by the rational method composer and provides process solutions to IBM for the development of the software systems and applications, agile practices and service management.
8. Rational method composer assists in capturing and maintaining the individuals’ own practices and further combines them with the practices and processes of IBM for achieving maximum result. 

One similarity that we can find in each and every project is that there is always a need to minimize the risk, ensuring the predictable results, delivering the high – quality results on time and so on.

Benefits of Rational Method Composer

- The practices provided by the rational method composer can be re-used for composing the process that is right – sized enough for meeting the specific requirements of the software systems and applications.

- The libraries of the rational method composer consist of the most robust practices.

- These practices are guidance for the software development, governance and management and can be very well applied to domains as well as the processes. 

- The following two libraries are shipped along with the rational method composer:

1. The IBM rational unified process 
2. The IBM practice Library

What are the default test plans attributes? How to define new test plan attributes?

Test plan is one of the important aspects of the silk test and is often characterized by some default attributes called the default test plan attributes. Well, the default test plan attributes are what we are going to talk about in this article. We shall also discuss how new test plan attributes can be defined. 

What is a Test Plan?

- A test plan forms the basis of the primary document that lays down the foundation for the testing that is to be carried out in a manner that is well organized. 

- Test plan is very important for the project managers as it is the document using which the testing projects can be managed well. 

- A badly drawn test plan is just same as not having any test plan.

- On the other hand, an intelligently drawn plan helps in smooth execution of the test cases and analysis of the other testing activities. 

- It would not be wrong to say that the test plan is actually a kind of dynamic document. 

- It acts especially in the spiral environments which have a tendency to change constantly. 

- The test plan is said to be a dynamic document since it changes according to the changes that occur in the software system or application. 

- Basically, a frame work is provided by the test plan which consists of a majority of the considerations that are made while planning. 

Attributes of Test Plan

Below mentioned are some of the attributes of a good test plan:

1. It stands a greater probability of catching majority of the defects of an application under test or AUT.
2. It provides greater test coverage for covering most of the test code.
3. It stays quite flexible throughout the testing process.
4. It is easy to be executed over and again automatically.
5. It properly defines the tests that are to be performed.
6. It lists out the expected results as clearly as possible.
7. It helps in reconciliation of the defects whenever a defect is found.
8. It helps in defining the objectives of testing.
9. It helps in defining the testing strategy in definite terms.
10. It helps in defining the criteria of test exit.
11. It always stays meaningful.
12. It never becomes become redundant.
13. It helps in identification of the risks
14. It helps in defining the test requirements as clearly as possible.
15. It helps in describing the test deliverable as clearly as possible.

Every test plan created is concluded with the following 3 steps:

1. Defining metrics
2. Conducting periodic audits as well as scheduling them
3. Approving the test plan

In the test plan view window, there is a tab titled “attributes” clicking on which will enable you to see all the project attributes that have been assigned to that particular test. Attributes can be thought of as an administrator created characteristics that are quite applicable to the tests. 

An attribute is defined as follows:

- item	Description
- Attribute	Name of the attribute
- value	Value that has been assigned to the attribute
- Type	Attribute type
- Inheritance	Whether or not the attribute is inherited

- The concept of inheritance in attributes is somewhat similar to what we have regarding the inheritance of success conditions and properties. 

- Attributes that are inherited throughout all the child test definitions and sub folders are assigned to a parent node. 

- To define an attribute follow the steps:

1. Open the test project.
2. Click define attributes menu
3. Click new button.
4. Enter the name for the new attribute.
5. Select the attribute type.
6. Click ok.