Thursday 29 November 2012

0 RAID 5 Data Recovery

Hello everyone! After a long break, today's topic is RAID 5 data recovery! First things first, let's start off with what RAID is. RAID (redundant array of independent disks) is a storage system where more than one disk is used. The data is distributed into those disks to prevent data loss in a case where one or more disks malfunction depending on which RAID level is used. There are different RAID levels from RAID 0 to RAID 6 (and RAID 10), each with different attributes.

Today, I will be specifically talking about RAID 5 since it's the most popularly used, (although being replaced slowly by RAID 6) and the safest RAID level.

Image from Wikipedia.

First things first, let's start with how storage space works in RAID 5. Let's assume we have 4 disks for this example, and our disks are 2 TB each. In this case, we would have 6 TB of space in this array, which is calculated by the formula X * ( Y - 1 ), where X is the smallest disk in this array, and Y is the number of disks. A minimum of 3 disks are needed for a RAID 5 array.

As you can see in the picture, the data is divided into 4 disks, which allows data on the different disks to be accessed simultaneously, which is an upside of the RAID 5 array.

With all that being said, now we can talk about the main point, which is RAID 5 data recovery. In RAID 5, the data is striped between multiple disks like we have talked before, and a parity bit is added to each disk (which are calculated between the cylinders) , which is the reason why we see a decrease in total storage space in the array. For those who don't know what parity is, I will explain really quick.

Parity in RAID 5, in simplest terms, are digits which contain information (calculated by XOR of data). But how does that help in order to recover lost data incase one of the disks malfunction? The answer to this is the XOR function. Using the XOR function on the undamaged disks' parity bits give you the parity bit of the damaged drive, which can be used to reconstruct all the data on the damaged disk. Since we brought that up, let's also see how XOR works.

XOR is the principle where if there's a difference between numbers, then the result is 1, and if they're same, the result is 0. Therefore 1 xor 1 would be 0, 0 xor 0 would be 0, 1 xor 0 would be 1, and 0 xor 1 would be 1.

Since we know how XOR works now, let's see an example. 

Drive 1: 010111001
Drive 2: 110011100
---------------------
Drive 3: 100100111 is found by using the XOR function. This means the damaged drive's parity bit is 100100111, and can be used to reconstruct the data on the disk. The same method can be used over and over for each disk, given that only ONE disk in the array is damaged. If more than one disk is damaged, then the XOR function cannot be used, which means RAID 5 will be ineffective.

Of course, there are billions of numbers and calculations being made in a real life case, and this is just a stripped down example in order to learn how RAID 5 data recovery works.

According to the things we talked until now, you can see RAID 5 has a big advantage in the name of data recovery, and is also a good system if the disks are being read more than written on (which I've mentioned earlier)

RAID 5 also comes with its disadvantages like everything else, and that's no surprise. Writing on a RAID 5 system will surely be slow, since the parity data should be kept updated all the time. Therefore, RAID 5 shouldn't be used in places where constant writing to the disks is applied. RAID 5 will also require more RAM, and it makes you lose some part of your storage space.

All in all, I believe RAID 5 data recovery is one of the most miraculous things to happen in computer history, since everything is being stored in computers in this age, and losing important data could be a matter of life and death for a company or a business owner. I'm sure many of you heard the term RAID and wondered how it worked, so I hope this article made you understand it in a better way!




Wednesday 21 November 2012

0 Making A Multiboot USB Stick

Hello everyone, today's topic is making a multiboot USB stick! I must say having a multiboot USB stick saved me a lot of time when I got in trouble with my current Windows installation. You can add many things to your multiboot USB stick such as a linux distro, a partition manager, MSDaRT, (this one saved my Windows so many times) hard drive utilities, rescue disks and so on depending on what you need.

Creating one is rather simple, and you're going to need the two programs above.

1) RMPrepUSB
2) SARDU

RMPrepUSB is the piece of software which prepares your USB Drive to be bootable, and SARDU adds the ISO files which contains the things you need on your USB stick.

After downloading both of them, we start by running RMPrepUSB. The settings in RMPrepUSB should be like the ones in the picture above.



After you selected these settings, click Prepare Drive and wait. Note that your drive will be wiped, so if you have anything important on the drive, make sure you get rid of them beforehand.

Now that we're done with making our USB stick boot ready, we can add the ISO files we want in it. Launch SARDU which we've downloaded beforehand.



Click the button which says ISO, and navigate to the folder where all the ISO files you want to add your usb stick are. (gather all the ISOs you want in one folder if you haven't done that yet)

Now you're ready to make your multiboot USB stick! Click the USB button on the right hand side, and wait until SARDU is done preparing your USB. (If SARDU has problems detecting your USB stick, use the Search USB button first)


And we're done! Now you have a multiboot USB stick with all the emergency system tools instead of having different CDs for them. When you're using the stick, make sure that your USB is the first boot option instead of your hard drives, cause then it's not going to work.

I hope this tutorial helped you, see you next time!

Thursday 15 November 2012

0 Cloud Computing

I'm sure many of you heard the term cloud computing a lot of times lately. Cloud computing is getting more popular every day and it's slowly taking over physical computing.. But what is cloud computing? That's probably the question all of you are asking if you're reading this right now.

Cloud computing, in most basic definition, is the usage of computer resources over a network, which includes internet. The computer resources could be anything depending on the type of the cloud computing, as there are many types of it.

Image from Wikipedia, created by Sam Johnston.


The most basic type of cloud computing is infrastructure as a service (IaaS). In this cloud computing type, you're basically given a computer which you can access via internet. These computers can either be physical computers or just virtual machines running on physical computers. IaaS is mainly used for the storage space, the ability to use different operating systems without altering your computer, being able to use an IP address of an another country, (for instance to be able to watch Netflix without living in US) and many more things you can do with a usual computer. In IaaS, you're only given the hardware and it's your responsibility to install the operating system, the software you need, to keep it updated and so on. Google Compute Engine is an example to this type of cloud computing.

The next type of cloud computing is platform as a service (PaaS). In PaaS, unlike IaaS, the operating system  and the features to test applications such as an execution environment is included. PaaS is used by application developers in order to test their software easily, instead of buying a new set of physical hardware to do so. Note that different PaaS providers support different programming languages, so you're supposed to find one which supports the language you are developing your software in. An example to PaaS is Google App Engine.

The ones who are familiar with gaming will know this one, which goes by the name software as a service (SaaS). In SaaS, a software is hosted on the cloud and it's accessed by people via a web browser. The upside of this system is that the software you're running via SaaS won't take any resources on your computer, since the computers in the cloud will be providing it. The first example I think of for this is certainly  Quake Live, as a gaming fan. OnLive is also a different example of SaaS cloud computing, and is considered as the future of gaming lately. SaaS is also used in different areas such as accounting.

STaaS must be the one that everyone is familiar with, unlike the others, because STaaS is being used by many home users. STaaS stands for Storage as a service, and is the principle behind many popular storage services such as Dropbox, Google Drive, iCloud and more. In this model, you're only given a storage space which you can access by using the internet wherever you have to.

There are many more types of cloud computing such as security as a service, database as a service, data as a service etc, which I won't be talking about right now, but maybe in the future.

I hope this helped you clear the question marks in your head about cloud computing!

Let's move on to the advantages of cloud computing now.

First things first, mobility is what makes cloud computing an amazing thing. You can't really have access to a physical thing all the time, but you can access your cloud wherever you want just with an internet connection. This plays a major role in the SaaS/STaaS system.

Second advantage would be cost, as it is cheaper than buying a physical computer to buy a cloud instead. IaaS and PaaS are the examples to this advantage.

Third advantage, in my eyes, is performance. You can always rely on big companies' cloud systems more than you can rely on your own home computer.

That being said, the only disadvantage which comes with cloud computing is the fact that if you don't have internet connection, you won't be able to access anything. But in the world we are living right now where even mobile phones are connected to internet 24/7 via 3G, where cities are covered in Wi-Fi coverage, I really doubt this would be a problem.

All in all, cloud computing has an answer for each one of your needs, if you are a home user, if you are a gamer, if you are a software developer, or if you are the owner of a business. I really believe it's the start of a new era in computing as it is growing so rapidly.

That would conclude everything I wanted to say about cloud computing for now, so see you all later in a different post!


Saturday 10 November 2012

0 Small But Powerful Software


Hello there! Today, instead of talking about a single thing, I decided to make a small compilation of software which I think would be really handy to have installed. You can pick whichever you want from the list and try it out to your likings. You might or might not have heard of these software, but I'm sure you wont leave them out of your toolkit once you got them.

Our first software is TeraCopy. TeraCopy is a file copying software which replaces the usual Windows one.



I don't know if it ever occured to you, but most of the times when you copy high amounts of files, or large files, the copying process either freezes or goes really slow. I've experienced freezing with Windows' own integrated copying software so many times, which made me look for an alternative. After using TeraCopy, I've noticed an increase in my copying speed, and also the freezing was gone. It's a great tool which should be installed right after formatting your computer, since it swaps itself with Windows' own copying software so you don't even have to run it. TeraCopy also features pausing/resuming which I personally haven't used so much, but I'm sure some people will find it useful.

You can download or find more about TeraCopy here.

Next up is Connectify, a software which saved my life many times. This one goes to the laptop users who don't have access to a wireless network. With Connectify, you or any of your friends who has a 3g/4g modem can turn the laptop into a wireless hotspot, and share the connection. I've experienced this problem many times when I went to holiday, and I was the only one who had a 3g modem. Luckily, I managed to share the connection with my family using Connectify.



Using Connectify is pretty simple and straight forward. All you have to do is choose a network name, a network password, and choose the connection which you want to share. Note that you will need the Pro version in order to share your connection, which I think is well worth for the money you're paying. Without Pro, you can only relay a WiFi connection, which is sort of useless if you have a router in the house.

You can find more about Connectify here.

I'm sure all of you know about Daemon Tools, but I'm sure I should mention it here. For those who don't know, Daemon Tools is a virtual cd/dvd-rom software, where you can mount CD/DVD files such as .iso or .cue in order to use them. Daemon Tools also lets you make images of the CDs or DVDs you own already, which you can use later on with Daemon Tools.



The usage is pretty simple again. All you need to do is to create virtual drives by clicking the DT plus sign in the main window, drag your iso files into the empty screen, and then mount them to the drives you want to by right clicking and selecting mount. The biggest advantage of this software is that you can create virtual copies of your CDs or DVDs, and keep as much of them as you want mounted with Daemon Tools instead of replacing a physical disk in your rom every single time. I personally find it such big of a hassle to replace a physical disk every single time I need to use something different.

To learn more about Daemon Tools, you can click this link.

This would be it for now, but I will be returning with a part 2 of this post after a while. I hope you enjoyed the read and found something which will make your life easier!

Tuesday 6 November 2012

0 Spotify - Music anywhere

Spotify is a music streaming software which is a must have for any music fan. (at least in my opinion!) With Spotify, you have access to millions of songs anytime you want, (provided you have an internet connection) without downloading them.



There are many great features about Spotify, but let's look at the subscription plans since the features change depending on which one you have.

Spotify Free - You have access to the songs, but you can listen to a song only five times until it gets disabled. You will also have ads inbetween some songs.

Spotify Unlimited - The ads will be gone, and the five time limit will be lifted compared to Spotify Free.

Spotify Premium - You will have offline mode, where you can add songs to your offline playlist which Spotify will let you listen to even without an internet connection. You will also be able to use Spotify on your mobile phone.

In Spotify, you have the ability to make as many playlist as you want, so you won't have to worry about categorizing. Talking about playlists, there's also a function called "collaborative playlist", where you can link your playlist to your friends and they can add songs into them as well, making it a great function for sharing music with friends.

There's also a pretty interesting thing called the Radio, which actually isn't a radio, but better. You simply choose a genre (or more than one genre), and Spotify starts streaming music which belong to those genres. The reason why I said it's better than a radio is because that you can actually skip the songs you don't like. It's a great way of discovering new songs and making new additions to your playlists.

The next interesting thing about Spotify is the App Finder, where you can download "apps" for your Spotify. There are many different apps for many different purposes, such as Moodagent, (my favorite one) TuneWiki,  and so on. These apps serve purposes like finding playlists you like, giving you lyrics of the songs you are listen to, and lots of different things.

Spotify also serves as a local music player. It will detect the local music files you have under a category called Local Files where you can play them, making it a great place to collect all of your music. You can also download the tracks you like off Spotify in exchange for a little bit of money.

Spotify also supports iPhone/Android sync through WiFi, which is an easy way to update the songs on your phone. Facebook integration is also supported in Spotify for the ones who are interested. (personally I'm not really a big fan of this, but I'm sure there are people who would like it.)

Lastly, you can always take a look at the Top Lists, where Spotify shows you the hit tracks, albums, and artist at the time. It's also a great way of finding new songs to listen to.

I've been using Spotify since the beta, and it's truly an amazing software. It's adding more features day by day, (there was no app finder, no Spotify Mobile, no top lists or anything similar back in the day) which surely looks promising. So if you like listening to music, if you like sharing music with your friends and family, and you want to have a big archive of music under your hand, then Spotify is the right choice for you!

I hope you enjoyed the read!






Saturday 3 November 2012

0 Dummy File Creator

Hello everyone! I wasn't planning on writing something today, but I felt the need to share a really interesting software which I've just stumbled upon a few hours ago. There's not much to say about it, as you will notice that it's a pretty simple software to use.

This one is called Dummy File Creator. You can download this software here in its official page.

As it is obvious from the name, this software creates dummy files, which basically aren't anything, but just things which take up space. All you need to do is fill the size box, and the software will create you dummy file(s) of that size.


I'm sure everyone has the same question right now. "What could be possibly a good use of this software?" That's exactly what I asked myself when I saw it, and then I started thinking to myself if I can do anything useful with this piece of software.

When you think about it, there are actually many great uses for this software. I remember the days I didn't do my projects in high school, so I just downloaded a random file and named it myproject.ppt, then told my teacher that the file was corrupted and I will bring my project the next day. 90% of the time, it earned me another day to finish my project. That's probably the best purpose I can think of for this program!

Putting the jokes aside, you can do things such as filling your hard drive to see if there are any problems in your hard drive's sectors, (you'll experience errors at some point if you have bad sectors) you can check the writing speed of your hard drive, you can make dummy files after you deleted something so that they become unrecoverable, (since the dummy files will be written on those sectors) and many more things that I can't think of right now, or that I shouldn't be speaking about here.

All in all, using this software and deciding what you're gonna do with it is totally up to your creativity. This is what I would call a simple, but a powerful tool.

I hope you enjoyed the read!
 

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