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Happy Independence day

Friday, 12 August 2011 06:25

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As we gear up to celebrate our independence day this year, amidst all the corruption news we hear everyday from the political fraternity, there is a marked sense of resignation among citizens of India. We tend to see anti-politician slogans in all corners of the internet. We urge netizens of our country to remain resilient, not to lose heart and continue to support our country in its progress in the 21st century. For we have never seen this unprecedented level of social awareness among the public about how the governance should happen. Perhaps, corruption levels were worse in the past but they never came to light due to the communication media not being so advanced as we have today.

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Storage Area Network in Cloud

Sunday, 07 August 2011 13:15

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A storage area network (SAN) is a dedicated storage network that provides access to consolidated, block level storage. SANs primarily are used to make storage devices accessible to servers so that the devices appear as locally attached to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the regular network by regular devices. The cost and complexity of SANs dropped in the early 2000s, allowing wider adoption across both enterprise and small to medium sized business environments. SAN now plays an important part in today's cloud hosting environments.


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VMware Vsphere - The Cloud OS

Monday, 13 June 2011 16:42

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VMware software provides a completely virtualized set of hardware to the guest operating system. VMware software virtualizes the hardware for a video adapter, a network adapter, and hard disk adapters. The host provides pass-through drivers for guest USB, serial, and parallel devices. In this way, VMware virtual machines become highly portable between computers, because every host looks nearly identical to the guest. In practice, a system administrator can pause operations on a virtual machine guest, move or copy that guest to another physical computer, and there resume execution exactly at the point of suspension. Alternatively, for enterprise servers, a feature called VMotion allows the migration of operational guest virtual machines between similar but separate hardware hosts sharing the same storage. Each of these transitions is completely transparent to any users on the virtual machine at the time it is being migrated.

VMware Workstation, Server, and ESX take a more optimized path to running target operating systems on the host than emulators (such as Bochs) which simulate the function of each CPU instruction on the target machine one-by-one, or dynamic recompilation which compiles blocks of machine-instructions the first time they execute, and then uses the translated code directly when the code runs subsequently. (Microsoft Virtual PC for Mac OS X takes this approach.) VMware software does not emulate an instruction set for different hardware not physically present. This significantly boosts performance, but can cause problems when moving virtual machine guests between hardware hosts using different instruction-sets (such as found in 64-bit Intel and AMD CPUs), or between hardware hosts with a differing number of CPUs. Stopping the virtual-machine guest before moving it to a different CPU type generally causes no issues.

VMware's products predate the virtualization extensions to the x86 instruction set, and do not require virtualization-enabled processors. On such older processors, they use the CPU to run code directly whenever possible (as, for example, when running user-mode and virtual 8086 mode code on x86). When direct execution cannot operate, such as with kernel-level andreal-mode code, VMware products re-write the code dynamically, a process VMware calls "binary translation" or BT. The translated code gets stored in spare memory, typically at the end of the address space, which segmentation mechanisms can protect and make invisible. For these reasons, VMware operates dramatically faster than emulators, running at more than 80% of the speed that the virtual guest operating-system would run directly on the same hardware. In one study VMware claims a slowdown over native ranging from 0–6 percent for the VMware ESX Server.

VMware's approach avoids some of the difficulties of virtualization on x86-based platforms. Virtual machines may deal with offending instructions by replacing them, or by simply running kernel-code in user-mode. Replacing instructions runs the risk that the code may fail to find the expected content if it reads itself; one cannot protect code against reading while allowing normal execution, and replacing in-place becomes complicated. Running the code unmodified in user-mode will also fail, as most instructions which just read the machine-state do not cause an exception and will betray the real state of the program, and certain instructions silently change behavior in user-mode. One must always rewrite; performing a simulation of the current program counter in the original location when necessary and (notably) remapping hardware code breakpoints.

Although VMware virtual machines run in user-mode, VMware Workstation itself requires the installation of various drivers in the host operating-system, notably to dynamically switch the Global Descriptor Table (GDT) and the Interrupt Descriptor Table (IDT). The VMware product line can also run different operating systems on a dual-boot system simultaneously by booting one partition natively while using the other as a guest within VMware Workstation.

VMware vSphere is a "cloud OS" utilized by LeelaHost's server infratructure. VMware vSphere 4 was originally named VMware Virtual Infrastructure (VI) 4 and is capable of managing large pools of infrastructure, including software and hardware both from internal and external networks.





 
   

Cloud Computing

Thursday, 12 May 2011 07:19

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Cloud computing refers to the provision of computational resources on demand via a computer network. Because the cloud is the underlying delivery mechanism, cloud based applications and services may support any type of software application or service in use today. Before the advent of computer networks, both data and software were stored and processed on or near the computer. The development of Local Area Networks LAN allowed for a tiered architecture in which multiple CPUs and storage devices may be organized to increase the performance of the entire system. LANs were widely deployed in corporate environments in the 1990's, and are notable for vendor specific connectivity limitations. These limitations gave rise to the marketing term "Islands of Information" which was widely used within the computing industry. The widespread implementation of the TCP/IP protocol stack and the subsequent popularization of the web has lead to multi-vendor networks that are no longer limited by company walls.

Cloud computing fundamentally allows for a functional separation between the resources used and the user's computer. The computing resources may or may not reside outside the local network, for example in an internet connected datacenter. What is important to the individual user is that they 'simply work'. This separation between the resources used and the user's computer also has allowed for the development of new business models. All of the development and maintenance tasks involved in provisioning the application are performed by the service provider. The user's computer may contain very little software or data (perhaps a minimal operating system and web browser only), serving as little more than a display terminal for processes occurring on a network of computers far away. Consumers now routinely use data intensive applications driven by cloud technology which were previously unavailable due to cost and deployment complexity. In many companies employees and company departments are bringing a flood of consumer technology into the workplace and this raises legal compliance and security concerns for the corporation.

A common shorthand for a provided cloud computing service (or even an aggregation of all existing cloud services) is "The Cloud". The most common analogy to explain cloud computing is that of public utilities such as electricity, gas, and water. Just as centralized and standardized utilities free individuals from the difficulties of generating electricity or pumping water, cloud computing frees users from certain hardware and software installation and maintenance tasks through the use of simpler hardware that accesses a vast network of computing resources (processors, hard drives, etc.). The sharing of resources reduces the cost to individuals.

The phrase “cloud computing” originated from the cloud symbol that is usually used by flow charts and diagrams to symbolize the internet. The principle behind the cloud is that any computer connected to the internet is connected to the same pool of computing power, applications, and files. Users can store and access personal files such as music, pictures, videos, and bookmarks or play games or use productivity applications on a remote server rather than physically carrying around a storage medium such as a DVD or thumb drive. Almost all users of the internet may be using a form of cloud computing though few realize it. Those who use web-based email such as Gmail, Hotmail, Yahoo, a Company owned email, or even an e-mail client program such as Outlook, Evolution, Mozilla Thunderbird or Entourage are making use of cloud email servers. Hence, desktop applications which connect to cloud email would be considered cloud applications.
 
 

ImageMagick Installation for PHP

Wednesday, 01 December 2010 10:29

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You need two components to make this work.

1.ImageMagick and its development libraries installed on the server.
2.Imagick.so which is the wrapper for php.

Imagick.so acts as a wrapper utilizing the native library that comes with ImageMagick library on the server.

To begin with you need to confirm all the latest ImageMagick modules and its libraries are installed on the server. The important thing to note is that 'pecl install imagick' will not work directly on the server. Nor will traditional steps given at,

http://forum.fdcservers.net/showthread.php?t=3392&page=1
OR
http://www.cpaneladmins.com/2009/11/10/how-to-install-imagick-for-php/

You need to install it manually with the latest ImagMagick library and the latest pecl from http://pecl.php.net/package/imagick.

1.Cd /usr/src/
2.yum install ImageM*
3.If you already have an ImageMagick library installed on the server, it is best you upgrade it. You can do so by 'yum reinstall ImageM*'.
4.After this you need to download the latest imagick native php extension from http://pecl.php.net/package/imagick.
5.wget http://pecl.php.net/get/imagick-3.0.1.tgz
6.At the time of writing this doc 3.0.1 was the latest version. Free free to modify with the latest after checking the build at the URL http://pecl.php.net/package/imagick.
7.tar -zxvf imagick-3.0.1.tgz
8.cd imagick-3.0.1
9.phpize
10../configure
11.make
12.make install
13.Once this is complete, the imagick.so file will have copied over to /usr/local/lib/php/extensions/no-debug-non-zts-20060613/ based on your installation.
14.Header files also will have copied over to /usr/local/include/php/
15.vi  /usr/local/lib/php.ini
16.Add “extension=imagick.so” to php.ini above.
17.Check phpinfo.php and it will now reflect the ImageMagick extension. phpinfo
 
   

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