Android 4.4 KitKat Hands On Review

Android KitKat was one of the most anticipated versions for 2013 due to the marketing strategy and other expected features.

Finally it was released in 1st week of November along with Nexus 5 release.

All Nexus 4 users, including me were waiting for the update since we heard about the new Google Now integrated launcher and ‘Okay Google’ stuff. But compared to other OTA updates, we had to wait for few weeks to get the Android 4.4 update. As usual, Indian users need to wait longer period and hence updated my device using Factory Image from Google Developer Site

Factory Images from Google – https://developers.google.com/android/nexus/images?hl=en

Experience

What did I see after upgrade? UI was more or less the same with 4.2 launcher. But, the size of the apps are reduced significantly and also the RAM usage.

My battery was draining faster and it became better after rooting and installing Greenify. I have seen many complaints from user about the opaque notification bar and big icons are missing in Nexus 4.

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There are links available to download ‘Google Experience Launcher’ or GEL which will give the Nexus 5 experience –

  • Swipe left to get Google Now
  • Google Search bar with ‘Okay Google’ option
  • Transparent status bar
  • Big icons

I also tried GEL and felt it was consuming lot of battery may be microphone will be listening all the time to hear ‘Okay Google’. Apart from that, no customization was possible including the desktop margins or changing the icons.

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Then I heard about KitKat launcher, which gives similar UI with more customization –Icons can be changed (with same Nova/Apex icon packs), remove the search bar in the home screen, disable left swipe for Google Now and reduce the icon size.

KitKat Launcher in play store – https://play.google.com/store/apps/details?id=com.kk.launcher

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What’s new in KitKat?

As far as I know, Google has made architectural changes in 4.4 to target devices with less RAM (even 512 MB). This will reduce the fragmentation issues since Android runs in both low end and high end devices. Ironically Google released few many versions of KitKat for various reasons

4.4 – 1st Factory Image – krt16o – 2nd week of November
4.4 – 2nd Factory Image – krt16s – November 3rd week – OTA version
4.4.1 – Patch – KOT49E – December
4.4.2 – Patch – KOT49E – December

Too many versions so far and it becomes difficult for other partners to start the roll-out.

Now, let me move on to the features

1) Dialer – This is a significant improvement – UI looks clean, search and favorite contacts in 1 page. Also search is integrated with Google database to list the local yellow page (I don’t need to view the number in Chrome and copy paste, instead directly type ‘Taxi’ and view local vendors)

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2) Hangout SMS – Hangout app will become the default SMS application and we can replace it with another SMS app. This is a nice feature since I don’t need to switch between 2 apps to send MMS and SMS

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3) Setting default Home screen – minor change in the Settings screen to change the default launcher

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4) ART – this is experimental stuff and may be running in beta or something; an option to switch the runtime between Dalvik and new Android Run Time. I did not find major difference in the performance since no graphic intensive apps are not installed in my phone.

ART Compatibility – All of my apps were compatible with ART except WhatsApp and it was resolved after updating 4.4.2

List of apps and status of compatibility – http://www.androidruntime.com/list

5) RAM – I was amazed to see the RAM usage after the upgrade; Nexus 4 has 2 GB RAM and only 400-450 MB was used by the background process. I have seen my friend’s Galaxy S3 that uses approx 1GB RAM and un-used Samsung process running in the background. I love Stock Android!!

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6) Location preference – We can see the apps that use Google location data and can switch based on need – Device only / Battery Saving / High Accuracy (Navigation works with this option alone)

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7) Lock Screen

 Music widgets (Google Play Music, Tune-In Radio etc) in the lock screen looks great in the full screen view

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8) Immersive mode

A new immersive mode is added in the library to view apps in the full screen without status bar and navigation bars. Only few apps like Google Play books have utilized the feature as of now.

Issues

I was lucky that I did not face the issues like – Google Dialer crashing / hanging and drastic battery drain (may be since I did not update via OTA)

Some of the minor issues faced are listed below

1) Media Server process – this process was running and battery was draining fast;

Followed below steps mentioned in Google Product Support Forums and I did not see the process again

A) Remove unwanted sync options – Currents, Google Play Music, Play Books, and TV etc
B) Stop the Google Currents process
C) Remove the dial and touchpad sound

2) Wi-Fi process – This process was running though I did not switch on Wi-Fi; switch off the “Scanning always available” option in the advanced Wi-Fi settings

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3) Rooting

I was aware that after each update, root access of the phone will be lost due to the firmware changes. But, after updating 2nd factory image, I was getting error while opening superuser. Tried flashing zip file multiple times using Clockwordmod recovery and result was same. Finally found solution from Google+ to try TWRP recovery to flash the zip and issue was solved

Below is the superuser versions used in various KitKat versions

Version 1.65 – Sup…erSU-v1.65.zip –4.4 – Factory Image – krt16o
Version 1.75 – UPDATE-SuperSU-v1.75.zip – 4.4 – Factory Image – krt16s
Version 1.80 – UPDATE-SuperSU-v1.80.zip – 4.4.1 and 4.4.2

Conclusion

Overall it is a great experience to use KitKat; Nexus 4 became smoother and faster; Battery life got improved. I did not feel any change in the Camera app or quality of the pictures though I read it happened in Nexus 5.

So that was my hands on review about Android 4.4. Hope you enjoyed it. Please leave valuable comments and share with your friends. Happy New Year!!

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How GPS Navigation and map works

Introduction
I have shared my experience with smartphones to be precise android phone through few articles. I am sure all smartphone users will agree with me that it will become part of their life – cos they are always connected through mail, social networking etc. Other than this, one of the most useful features is Maps and Navigation.
This article is to find to know how GPS (Global Positioning System) Navigation, Google maps works
How it works
GPS Navigations was widely used in vehicles and portable devices by hunters and hikers. Now it is essential part of a very basic smartphone. How this technology works?
All GPS enabled devices have a small receiver (antenna) and it detects where we are and there need to be a infrastructure to support this. GPS was originally created for military use and 1st satellite was launched in 1978.
Since then, they’ve created a constellation of satellites orbiting the earth. There are around 50 satellites and around 30 of them are active. GPS satellites orbit the globe twice a day and sends low-power radio signal; also the orbits are arranged to make at least 4 satellites visible.
GPS receivers can receive the signal from satellite and calculate the location (altitude) based on traveling time of signal. But this is not enough to show the location. There need to be a database to cross reference the location and show actual landmarks and streets. This is done by the third party software. NAVTEQ and Tele Atlas are 2 biggest database providers
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Smartphone should be in visible to at least 3 satellites to calculate exact location. This operation is based on a simple mathematical principle called trilateration: – this is a vast topic and outside scope of this blog.
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For accurate location, the device should be in open area, clear view of sky and there need be powerful GPS antenna.
Internet connectivity
To use the GPS in there should be an active connection to the network to download the map data (GPS only tells you where on that map you are, it carries no map image data). If the maps cached on phone, when losing data connection navigation still works. However, if there is no connection and the phone is moved to an area  where map data is not downloaded , map will fail.
More details into GPS receivers
GPS receiver works the same way a cell phone works. A cell phone is basically a sophisticated 2 way radio. Towers and base stations, arranged into a network of cells, send and receive radio signals. Cell phones contain low-power transmitters that let them communicate with the nearest tower.
As we travel, phone moves from one cell to another, and the base stations monitor the strength of phone’s signal. As phone move toward the edge of one cell, signal strength diminishes and in the same time, the base station in the cell phone is approaching notices the strength of signal increasing: – the towers transfer phone’s signal from one to another
Like a cell phone, a GPS receiver relies on radio waves. But instead of using towers on the ground, it communicates with satellites that orbit the Earth.
Even without a GPS receiver, cell phone can provide information about location. A computer can determine our location based on measurements of your signal, such as:
1) Its angle of approach to the cell towers
2) How long it takes the signal to travel to multiple towers
3) The strength of your signal when it reaches the towers
Google Maps and Navigation
Being and android and Google fan, I’ve mostly used Google Maps, Navigation and Earth, which are free and yet awesome.
Some details about Google maps: – the data is compiled by its partner Tele Atlas, which is the world leader in navigation and location based services. The maps are highly accurate and have been hailed for recording extremely rural areas and mapping the terrain correctly. Business and premises which are place-marked on maps have been supplied by directory listings.
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Google maps latest update allows the user to save the map to make it available offline. Also I have mentioned about previous release in which inside building view for selected airports and shopping malls. Also the 3D map will be released soon. But in country like India, where 3G is a luxury, this does not make any senseJ. Let’s wait till 2020!!
The End
Hope you guys enjoyed reading and add please send your feedback through the comments section

Google Chrome vs Internet Explorer (Why Google Chrome is better than Internet Explorer)

It’s been more than a year I’m using Chrome and never wanted to go back to days of IE. I have recommended this to many friends and they had similar experience

 Why I like or feel Chrome is better? Here are the reasons that I have explored so far (comparing Chrome 23 with IE 8)
Chrome
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Internet Explorer
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1) Chrome is lightweight and fast
I can feel the difference while launching the browsers: – IE have a lag and it’s very bad in my office due to so many restriction rules written, entire browser hangs up). Auto-complete feature is awesome in Chrome and we can customize this with any search engines. See the results in 2 browsers when typing “fl”
Chrome
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Internet Explorer
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Chrome is powerful while booking railway tickets. All Indians who have traveled in train will know how difficult to get TATKAL tickets (train tickets that can be booked only 1 day in advance) since millions connect at the same time. Though I don’t have any proof or know the reason, Chrome is better for TATKAL tickets (Go to Settings – Advanced Settings – Disable “Predict network actions to improve page load performance”). Chrome will wait for longer time to get the page rather than giving 403 errors
Print – Chrome allows me to download as PDF, while IE gives me no-printer error (very helpful when i don’t have printer with me)
Chrome
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Internet Explorer
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2) Tabs & copy text
These are 2 small but useful featuresTabs in chrome can be easily separated from main window, no need to start a new window.

Copy text – Its very easy to copy a part of text from paragraph in Chrome :- select the text and press right arrow to highlight and this does not work in IE

3) Favorites / Bookmarks
This is my one of the favorite feature in Chrome. Adding to bookmark is very easy – click on star icon on the top of the page. Once bookmarked, the yellow star will be shown in Chrome. There is no way to know a bookmarked page in IE. The bookmark manager interface is also really cool in Chrome
Chrome
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Internet Explorer
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4) Downloads
Another unique feature, all downloads can be viewed and managed in single window. Even we can pause the individual file downloads and prioritize. Also I can set the destination folder to avoid the target confirmation on each download
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5) Multiple Account
You can add multiple Google accounts and manage all personal data including history, bookmarks etc. I explored this feature after hearing regular complaint from my wife about difficulties in using IE.Steps to add and switch account

1) Click on top right icon and go to Settings
2) Navigate to Users tab
3) Click on Add New User – enter Google account name and password
User icon will be visible on left top corner

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4) Select the icon to switch to different account
6) Incognito window
Good one if you want to browse without leaving history behind
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7) Web store
Unique feature – can play games like angry birds, cut the rope by visiting Chrome web store and adding them to my browser
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Chrome is dong well in smartphones too – it was one of the top downloads in Apple store after the launch. Its compatible in Android 4.0 + devices and loving it in my tabSo, that’s my experience. Have you tried Chrome and felt the same difference? Or did you find more useful features of Chrome? Feel free to write your comments… Thanks for reading

Best movies and songs of 2012

My blog was started for TES – Technology Entertainment and Science. But I did not do justice to entertainment since I have written only 1 article in that.
Let me compromise a bit – an article about my favorite movies and songs in 2012 – which I never want to miss. Some of them may have released before 2012, but I’ve heard them this year and thanks to my music freak cousin for sharing most of them
Also it is my personal opinion and I don’t discount other songs and movies at all

Try the songs and movies listed (if you haven’t done yet) – hope you will enjoy it!!

Songs

1) Deshay Basara – Moroccan Arabic – BGM in Dark Knight rises –Music by Hans Zimmer
Entire OST and BGM is rocking and this one is the best…gives you goosebumps for sure

2) Nenjukkulle – Tamil – from Kadal movie – sung by new singer Shakthisree Gopalan
Truly marvelous and the well presented in the MTV unplugged –

nenjukkulle

3) Allah hi raham – Hindi – MTV Coke Studio – sung by Shankar Mahadevan
This song was out in 2011, but I heard it along with Coke Studio 2 – truly remarkable singing – no words about Shankar – he is a genius who can sing Hindustani and Classical –

AllahHi

4) Madari – Hindi – MTV Coke Studio – sung by Vishal and Sonu Kakkar
Excellent presentation by Vishal and superb guitar –

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5) Banjara – Hindi – MTV Coke Studio – Vijay Prakash and Nandini
After hearing this, you will understand Vijay is an unsung HERO – classical portion is amazing –

Banjara

6) Yeh jo des – Hindi – MTV unplugged – sung by the maestro Rahman itself
The original was my favorite till Swades – he improvised it – mind blowing –

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7) I believe – Hindi/English – The DEWARIST – sung by Agnee , Parikarma and Shilpa
Inspiring lyrics , nice blend of guitar and voice –

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8) Sail – English – AWOLNATION
Heard this song along with Felix baumgartner’s space jump – song is amazing and well suited with the mission –

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9) Gangnam Style – Korean – sung by PSY
Wow…this was a surprise of 2012, the song was a instant hit, millions of views – the song proves music will break all barriers – any age group can enjoy this and PSY taught us simple dance step too –

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10) Subhan Allaha – Malayalam – Ustad Hotel – sung by Navin Iyer
Amazing song with Sufi and classical blend –

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11) Pareshaan – Hindi – Ishaqzaade – sung by Shalmali Kholgade
Nice song with rock blend

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12) MTV Coke Studio Season 2 – whole program is amazing –
http://www.cokestudioindia.com/season2/

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14) Kyon – Hindi – Barfi – sung by Papon and Sunidhi
Another superb song from Papon – he deserves more songs

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Movies

1) The Dark Knight Rises – English – directed Christopher Nolan
2nd best of triology – what a way to end an epic –
http://www.imdb.com/title/tt1345836/

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2) Gangs of Wasseypur – Hindi – directed by Anurag Kashyap
A masterpiece – Godfather’s indian version –
http://www.imdb.com/title/tt1954470/

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3) Paan Singh Tomar – Hindi – directed by Tigmanshu Dhulia
Class acting by Irfan Khan –
http://www.imdb.com/title/tt1620933/

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4) Barfi – Hindi – directed by Anurag Basu
Loved because of Ranbir’s acting and screenplay
http://www.imdb.com/title/tt2082197/

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5) Pizza – Tamil – directed by Karthik Subbaraj

Expect the unexpected!! – Different experience – http://en.wikipedia.org/wiki/Pizza_(2012_film)

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6) Ustad Hotel – Malayalam – directed by Anwar Rasheed

Superb movie – awesome background music and powerful performance by late Thilakan

There was also number of superb movies includng 22 Female Kottayam and Spirit..but this is special because of Thilakan’s performance
http://en.wikipedia.org/wiki/Ustad_Hotel

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Last One – Zeitgeist 2012
2012 happenings – video compilation – really amazing

So, do you agree with my choice ?? Please post your opinion and comments…

Hope there will be good music and amazing movies in year 2013 … Happy New Year J

Mobile communication – infrared, Bluetooth and NFC

Yesterday I was trying to send some videos with 200 MB data to another mobile. Though it happened smoothly, one question came to my mind. I have used this technology every day, but did not try to understand about it yet.
It made me very happy too since I got my topic!!

Infrared, Bluetooth and now NFC – all these technologies had done its part in different period. I used to remember keeping 2 Nokia phones in the straight line to transfer an image. Now it’s just a tap away. Here are some details about each technology – one is outdated, one is widely used and we yet to know the potential of last one.

Infrared
As the name indicates, the communication is established via infrared signals. This technology is used by most of the remote controls. This technology is device specific and there should be direct line of sight between (max 3 feet) transmitter and receiver. This communication is more secure since it can be intercepted by a device and it’s one-to-one.
I’m not going to more details about this technology since it is not used in mobile devices anymore

Bluetooth
Compared to infrared, Bluetooth devices can work together, its omni-directional. Current devices can transfer in the range of 30 feet. Bluetooth uses radio frequency and hence transmission is possible through walls or other objects and hence it is widely used in computers, PDA, headsets, mobile handsets etc. These devices can communicate with each other irrespective of the manufacturer since it is using standard 2.4 GHz frequency (ISM – Industrial Scientific and Medical devices – band).

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Bluetooth communication does not need user intervention and uses very little power: – we connect devices such as phone, car GPS, mobile, PC and control them smartly (it automatically switches to the appropriate devices – handsfree is an example, if you setup devices in car audio and home land phone, the call switched automatically to these devices …pretty cool rite?). Current devices can transfer data up to 3Mbps (2.0 devices).

As I said earlier, it works in RF and lot of other devices such as cordless phones, baby-monitors, garbage door openers too are using same ISM band. Bluetooth uses very weak signal of 1 milli-watt to avoid interference and hence limits the range to 30 feet. Also it can connect 8 devices simultaneously and uses spread-spectrum frequency hopping method to avoid interference with each other (too technical, so no details).

Like other wireless network, Bluetooth also faces security issues since hackers can try to grab your data or interfere with signals with same frequency. Bluetooth offers several security options to avoid this – allowing only trusted devices, making the devices non-discoverable, pairing etc. Similar to hacking there is bluejacking – sending a business card as text message, contact added in address book by mistake and the hacker gets the control of the address book and phone.
BT communication can be done with a computer and other devices using a USB-dongle (most laptops have added this in-built)

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NFC
Near Field Communication a.k.a NFC is the current hot topic in the smartphone market and it takes communication to the next level. I don’t think it is a replacement for BT, but NFC is preferable in some places.
In simple words, BT is like a phone communication – sender and receiver should be available and NFC is like an e-mail – we can transfer some information to a device (called tags) and then this can be used in any other device

As the name (near field) indicates, maximum distance for communication is only 4 centimeters. NFC can interact with other device with a single wave and it’s faster compared to BT (needs only 1/10 seconds to establish).
It also reduces the security risk specified in case of BT and NFC needs minimal power compared to BT. The speed of NFC is only 424 kbit/s and it can be used in combination with BT to speed up the process.

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NFC can make use of un-powered chip called as tag to communicate – that’s why I said, its like an e-mail. Many vendors are creating these tags and X-peria smart tags are one of the popular one. You can save your phone settings, or browser bookmarks to a tag and this can be restored in any other NFC powered devices. NFC is similar to RFID (radio frequency identification) technology.

Android and NFC
Android uses NFC technology as Android-beam and this was launched in Android 4.0 ICS. They have customized the technology and made data transfer a dream – just swipe or touch the devices. It also supports technology called Wi-Fi Direct, previously known as Wi-Fi P2P. As the name shows, your mobile device can do peer-to-peer networking and transfer data. I think this is the coolest feature of NFC (torrent in smartphone?)

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NFC, Android beam, S-beam have so-many features and I have to include them in another article. We can expect more stuff in NFC since it’s in growing stage and Android 4.1 jelly bean is already started hitting the market. I pity I-phone users since they can’t try these stuffs in near future

The End
I guess you got an overall idea about some of the most important communication/transfer technologies we have used so far. If you like it, post your comments and keep reading!!! Thanks

Reference
http://www.careerride.com/bluetooth-vs-infrared.aspx
http://www.howstuffworks.com/bluetooth.htm
http://www.swedetrack.com/images/bluet13.htm
http://www.nearfieldcommunicationnfc.net/nfc-vs-bluetooth.html
http://iphone.appstorm.net/general/hardware-news/what-is-nfc-and-why-should-i-care/
http://en.wikipedia.org/wiki/Near_field_communication
http://www.firstpost.com/tech/no-nfc-in-iphone-5-heres-why-apple-gave-it-a-miss-455129.html
http://www.guardian.co.uk/technology/2012/sep/14/apple-iphone-5-near-field-communication-nfc
http://nfctimes.com/news/samsung-unveils-galaxy-s-iii-supporting-nfc-payment-and-enhanced-p2p
http://en.wikipedia.org/wiki/Wi-Fi_Direct

Cloud computing vs. Server virtualization

I hope you have read my previous articles: Cloud computing – an insightServer virtualization – Basics and got idea about these 2 most happening topics in IT industry. Now let’s see the difference between these 2. 

Comparison

1) Virtualization is the deployment of existing infrastructure to do more service through shared mechanism. Also it can be considered as a sub-set of cloud computing. Cloud computing is an approach to consolidate IT infrastructure across enterprises which can be deployed on shared service model. Virtualization is an abstraction for the hardware layer to run more virtual machines on single physical machine. 

2) Virtualization is a technical term; it’s for IT-Administrators and not governed. Cloud computing is Business; it’s for all, and it’s governed.

3) Virtualization focuses on leveraging the IT infrastructure in an optimal fashion to reduce operational costs. The software like XEN, VMWare allow different applications and OS to be consolidated on the same physical machine. Cloud computing is to deliver computing resources and software as on-demand pay-per usage basis. Companies opt to buy such services from service providers rather than hosting them in own data centers. 

4) Virtualization helps to make cloud computing a reality (both public and private cloud). Cloud model is strategic decision to of moving from traditional model “cook and eat” to service oriented model “eat from restaurant” which is more efficient, flexible and simple (pay for what we use).

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5) Both technologies are developed to maximize the use of computing resources with minimal cost, though the approaches are different. Also both can save money in different ways. Virtualization may be used to provide cloud computing.
 
6) To implement virtualization, organizations need upfront cost since it involves purchase of servers and infrastructure. There will be large capital cost involved, but the money will be saved over a period. Cloud is the opposite of this. This means organizations can start using the resources with less capital cost. But as the applications becomes popular and uses more resources, it might become more expensive than setting up own virtual infrastructure. 
Implementation of cloud also depends upon credibility / good-will of the service provider (vendor) since the data will be residing in their servers. But in virtualization, the organization has more control in the data back-up, disaster recovery mechanism etc. History: Microsoft’s data center, which provides T-mobile’s sidekick service, was crashed in year 2011. The customer data was lost and it was huge blow to T-mobile reputation.
 
The End
 
In 3 articles, I was trying to focus more on the fundamentals or basics of 2 concepts. Now I gonna start my journey to the core of these subjects: – architecture, implementation, layers, infrastructure etc and blog more. 
Bye till then !!!
 

Virtualization – Basics

Virtualization – another term like Cloud computing, that we hear in recent past and I want to put down some interesting details about it. This can be considered as a scaled down version of cloud computing, lets see the details

Introduction

Let’s take a scenario – I am running a small IT firm with 10 employees and I need to buy infrastructure for running the firm. I need to buy server, 10 desktops, software (all licensed), hire administrators to maintain servers etc. If I decide to hire more employees, I have to buy more desktops for their needs and spend more money and this becomes a cumbersome process for me. Instead of buying 10 desktops with high configurations, I thought of investing in one high end machine (lots of CPU, RAM and space) and create 10 virtual desktops for each employee. In this approach, it is very easy to allocate one more virtual environment as I hire more and more employees. Hope you understood the very basic concept of virtualization and its benefits. Now let’s take a deep dive into the topic (more details in server virtualization)
 
Why virtualization?
 
Due to mobile computing and other applications, the Servers need to be very powerful with CPU and multiple processors to run complex tasks. Network administrators dedicate each server to a specific application or task (DB, Web, and Network etc) since many of these tasks will not comply with others and it becomes a difficult task to manage them.
Though servers are dedicated for each application, they may not be utilized to its capability with regards to processing power and storage. Also servers will take lot of physical space, generates heat and data center becomes crowded with racks. Virtualization can address these issues since physical servers are converted to multiple virtual machines.  This is not a new concept since this approach was done in Super computer decades ago and in last few years this became feasible for servers.

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There are different types of virtualization – Hardware, Desktop, Software, Memory, Storage, Data and Network. I am more interested in Hardware, Software and Desktop virtualization and will talk about it more.
 
Hardware (Server Virtualization) – Also known as platform virtualization refers to the creation of virtual machine that acts like a real computer with an operating system. Software executed on these virtual machines is separated from underlying hardware resources. A computer running in Microsoft Windows may host a virtual machine which looks like computer with Linux OS. There are 2 parties in this virtualization
 
Host Machine – Physical server in which the virtualization takes place; Software or firmware that creates a virtual machine on the host hardware is called Hypervisor / Virtual Machine Monitor
 
Guest Machine – Virtual machine and they behave like physical machines and does not need much processing power or storage.
 
This virtualization can be created in 3 ways
 
Full virtualization – Uses special kind of software called Hypervisor and this interacts directly with the physical server’s CPU and disk space. It serves as a platform for the virtual server’s OS and also keeps each virtual server completely independent and unaware of other virtual machines.  Also each virtual machine runs in its own OS and that means one can run in Windows and other in Linux.
 
Hypervisor monitors physical server’s resources and relays it to the appropriate virtual server as the virtual machine runs applications. It takes some resources to do this action and it might affect the overall performance of the server as the number of virtual machines and applications grow. This method is commonly opted by most of the organizations since servers can run on different OS and also more support is available.
 
 
Para-virtualization – This is similar to full virtualization, but the Guest is aware of other virtual machines. The same Hypervisor software is used, but does not need much resource to manage guest OS since each guest is already aware of demands of other OS placing on the physical server. Administrators can choose this method if the servers are running in different OS, but this technique is relatively new and only few companies offer the software.
 
OS Level virtualization – This is again similar to full virtualization. This does not need Hypervisor software, but the virtualization is part of the host OS which performs all functions (same way it is done in full virtualization). All guest servers must run on the same OS and each remains independent of others. Organizations can prefer this approach if all physical servers run on the same OS since it’s faster and more efficient than other methods.
 
Advantages
 
·          Redundancy without purchasing additional hardware
·          Safety – if one server fails, another server running same application can replace it
·          Offer isolated, independent systems in which programmers can test new applications or OS.
·          Environment friendly – conserve space, storage and less heat will be generated by server.
·          Migration – With the help of Third party hardware and software, virtual servers can be moved from one network to other. 
 
 
 
Limitations
 
 
·          Network administrators should study the network architecture and needs before attempting a solution
·          Virtualization cannot be implemented in servers which has heavy load (high demand of processing power) since the server’s CPU is divided among virtual servers. Server may become very slow also might crash as the demand of applications increase in virtual machines.
·          It is not a good idea to create too many virtual servers in one physical server since it will create overload. Also processing power and storage allocated to each server will be divided and virtual server may not satisfy the business need.
·          Migration is another big challenge since its possible to migrate one virtual to another if both use same manufacturer’s processor due to technology limitations.
 
 The End
 
More and more organizations are opted this technology in recent past. Virtualization products are offered by major companies like Microsoft (VMWare), IBM (Blade), and Symantec etc.   
 
In my next article, I am gonna write about Cloud computing vs. Virtualization