Segmentation Fault

  OS extends its physical memory by using virtual memory which is implemented using a technique called paging. Paging is another form of swapping between HDD and Physical Memory. If application requests a page in memory and it could find it then a Page Fault occurs. If the address of the page requested is invalid […]

When you hit URL in browser

The 3 things that happens: 1.DNS Resolution 2.TCP connection 3.Browser Rendering 4.HTTP Request/Response   DNS Resolution http://www.example.com on Browser The operating system looks at /etc/host file,first for the ip address of http://www.example.com(this can be changed from /etc/nsswitch), then looks /etc/resolv.conf for the DNS server IP for that machine nameserver 172.16.200.30 nameserver 172.16.200.31 Pick 172.16.200.30 (call […]

Is iSCSI SAN or is iSCSI NAS?

The two big differences between NAS and Fibre Channel SAN are the wires and the protocols. In terms of wires, NAS runs on Ethernet, and FC-SAN runs on Fibre Channel. The protocols are also different. NAS communicates at the file level, with requests like create-file-MyHomework.doc or read-file-Budget.xls. FC-SAN communicates at the block level, with requests over the wire like read-block-thirty-four or write-block-five-thousand-and-two.   If […]

Links worth Noting

    Active FTP vs. Passive FTP, a Definitive Explanation AWS for Dev and Test – part 3 Performance Testing by Just Eat OSSEC Installation. Apache Internal Dummy Collection. Nginx and Heartbleed

PyBash

Identation, is what important in Python. Python can be used for both CGI and Scripts Python scripts are usually stored in file with .py extension. In linux there is no significance with any extension. It is just naming convention to understand that the file contains python script. In python script – mention the python shebang […]

Stack Optimization for Magento

Caching is always the First Step towards performance enhancement. Why use Redis for Magento? Lets have a look at how the Magento caching (which uses the Zend_Cache library) works. Each cache entry consists of the following information the cached data a cache key (or ID), that uniquely identifies this entry and is used to retrieve […]

Identify Memory Leak

A memory leak, technically, is an ever-increasing usage of memory by an application. With common desktop applications, this may go unnoticed, because a process typically frees any memory it has used when you close the application. However, In the client/server model, memory leakage is a serious issue, because applications are expected to be available 24×7. […]