Storage
What is Deduplication/Synthetic backup
What is Thin Provisioning
Click to know more...
TCP/IP, SAN, NAS, Zoning, iSCSI, FC, FCOE
Telecom
RAID Levels
The standard RAID levels are a basic set of RAID configurations and employ striping, mirroring, or parity. The standard RAID levels can be modified for other benefits (see Nested RAID levels for modes like 1+0 or 0+1); there are also non-standard RAID levels, and non-RAID drive architectures, which may be offered as alternatives to RAID architectures. RAID levels and their associated data formats are standardized by SNIA in the Common RAID Disk Drive Format (DDF) standard
Ques. What is difference between Multitasking, Multiprocessing and Multi-threading?
Ans. A task and process are the same thing. A single task Or process can have multiple threads (see task manager in windows).
Multitasking refers to the ability of the OS to quickly switch between each computing task to give the impression the different applications are executing multiple actions simultaneously. Switching between different processes called context switching.
Multithreading extends the idea of multitasking into applications, so you can subdivide specific operations within a single application into individual threads. Each of the threads can run in parallel. The OS divides processing time not only among different applications, but also among each thread within an application.
Applications that take advantage of multithreading have numerous benefits, including the following:
More efficient CPU use
Better system reliability
Improved performance on multiprocessor computers
Ques. What is difference between service and process?
Ans. A process is any piece of software that is running on a computer. For example, your anti-virus software runs in the background as a process, which was automatically started when the computer booted. Some processes start when your computer boots, others are started manually when needed.
If you're familiar with Unix, a Windows service is like a Unix daemon. It isn't associated with any particular user, and is always running in the background. Services do not have user interface, they just run by operating system. Normally processes have user interface.
Some processes are services that publish methods to access them, so other programs can call them as needed. Printing services would be an example of a service type of process, where your email program can just call the print services process to say it wants to print, and the service does the actual work.
OR
The main difference is that a windows service is something you want to run as a background service and doesn't require a UI. An example is a service that indexes files on your drive for searching.
Another benefit is you can have services automatically start when the user logs in. There are also methods you can override that are called when the service is started/stopped (ie. from Control Panel | Administrative Tools | Services).
OR
The key difference between a process running as an application versus as a service is that the service can operate entirely outside the normal association with a user and session. Thus services can run such that they start before any user logs in and can continue running after users log off. Services are thus used to implement a great deal of the actual functionality of the operating system.
Services are also not tied to running as a 1:1 mapping with a process. Many services can exist within one process, normally through the use of svchost (take a look at these with process explorer for an indication of how this often works). This reduces the effort at startup as multiple processes are not required for relatively lightweight services.
Implementing a service in c# is pretty simple, this page indicates how in very easy to follow terms.
Note that in reality a service in windows is little more that the scaffolding in the registry under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services which defines those 'image paths' (in most cases simply executables and the parameters to use) which are considered services along with which user then run as, which other services they depend on and whether they start at start up/post start up or as required.
Ques. What is difference between multi-core and multi-processor systems?
Ans. Multi core processors have two cores that can handle executing processes on one chip. Typicaly each core has its own L1 cache and the they will share L2 cahce. These chips are found in PC and Laptops now a days. Multi processors are multiple chips that are pluged into the mother board, each chip with have its own cache and none of it is shared. These are usually used in server applications or for developers. They are not for gaming and most home users (there are always exceptions).
When running on a multicore system, multitasking OSs can truly execute multiple tasks concurrently. The multiple computing engines work independently on different tasks.
By 'chip' means complete CPU that gets plugged into a socket on the motherboard. On many modern processors however the memory controller is built into the physical die that contains the CPU, like on the i5, i7, and AM2 and AM3 chips.
Well the core IS the pipeline alone with a register set to store program state. And in modern processors the L1 instruction cache is usually pretty integral to the core too since it typically stores pre-decomposed micro-operations.
Whether you call it a "pipeline" or a "core" is perhaps just a matter of personal preference - the important thing that it's what's needed to execute a stream of instructions. If it's got 4 o' them thingies then the chip can be running four instruction streams at once.
Where it gets blurred is with hyperthreading, which basically takes one pipeline and gives it two sets of registers so that it can maintain two discrete program states. The idea is to feed two streams of instructions through the same pipeline, each using their own discrete registers to take advantage of execution units (adders, floating point units, etc) that might otherwise go idle.
Read this PDF file (See attachment P4_CPUArchitecture.pdf)about the microarchitecture of the Pentium 4. The Pentium 4 is out of date, but the reality is that pipeline concepts haven't changed a whole lot since it came out, and this article provides a pretty good description of all the things that are done in the pipeline of a modern CPU.
Click to know more : http://www.tomshardware.com/forum/270043-28-difference-multicore-multiprocessor