Tutorial 4: Redundant Arrays for Inexpensice Drive- " RAID"

What is RAID?

RAID is the idea of combining multiple small and inexpensive disk drives into one array, which would result in a higher performance of a “Single Large Expensive Drive (SLED). Besides, this array of drives seems to the computer as a single drive.

In order to find the perfect RAID, you will need, first, to identify your needs.  

There are different types (levels) of RAID’s:

RAID 0 (striping):

-A disk that increases performance by interleaving data across two or more disk drives.

-Data are broken into blocks, called “stripes”, in order to increase speed (Data is written on both drives simultaneously)

For example:

If you are writing the word DATA:

DA= would go on the 1^st drive

TA=would go on the2nd drive

NOTE: Example is only using 2 disk drives. Keep in mind that the more disks, the faster RAID 0 works, and the higher percentage of failing.

*There is only one huge problem using RAID 0; no redundancy exists.

In other words, if one disk drive fails, data is automatically lost.

Key factors:

Advantage: high performance

Disadvantage: no redundancy

Ideal for: highest resolution HD, and temporary storage.

RAID 1 (mirroring or duplexing):

-RAID 1 uses a pair of drives

-RAID 1 is always implemented as mirroring; data is copied on both drives using either a hardware or software.

-Redundancy exits; if one drive fails, the other one keeps working as a single drive, until the death drive is replaced. In other words, data is not lost.

For example:

If you are writing the word DATA:

Drive 1: DATA

Drive 2: DATA

*Data is been written simultaneously on both disk drives.

NOTE: Once one of the disk drives fails, you need to replace it, and re-mirror the data to the new disk drive.  System keeps running at same speed even with one disk drive.

*It is very important to know that we can use a hot spare disk. A hot spare disk is a 3^rd disk doing absolutely nothing, until one disk fails. Basically, this hot spare will replace the death disk.

*A variant of RAID 1 is duplexing, which duplicates the controller card as wells as the drive, providing tolerance against failure.

Key factors:

Advantage: high redundancy

Disadvantage: expensive (cost per GB is doubled)

Ideal for: maximum disk failure protection, enterprise servers, and small database systems,

Fault tolerance: very good; better duplexing

Array capacity: size of smaller drive

Availability: Most RAID controllers will support hot sparing and automatically rebuild RAID 1

RAID 3 (striping with a dedicated parity drive):

-Raid level 3 stripes data at a byte level across several disk drives, with parity stored on one drive

-Byte level stripping requires hardware support for efficient use

-RAID level 3 can be used in data intensive or a single-user environments which access long sequential records to speed up data transfer

-RAID level 3 does not allow multiple operations to be met in order to avoid performance degradation.

Key factors:

Advantages: Efficient drive redundancy (one drive only used for parity)

Disadvantages: Loses one disk drive capacity

Ideal for:  Well-balanced for video requiring redundancy and performance

RAID 5 (stripping the parity across all drives):

-RAID level 5 is considered one of the popular RAID’s due to its block level stripping with distributed parity.

-RAID 5 requires three or more drives

-Data blocks are spread across all drives except one

-RAID 5 allows better parallelism in a multiple transactions environment.

-Fault tolerance is kept by guaranteeing that the parity information for any given block of data is placed on a drive separate from those used to store the data itself

-Performance of RAID 5 can be adjusted by trying different stripes sizes.

   

   1. Fast reading speed (similar to RAID 0)

   2. Moderate writing speed (CPU must spend some time in computing parity)

-If single drive failures; no data is lost (but system is running slower)

-Death disk drive needs to be replaced; system allows reconstructing data on the new drive before another failure occurs (Mr. Olson)

-Hot spare disk can be used

Key factors:

Advantage: Efficient drive redundancy; parity distributed to all drives.

Disadvantage: one disk drive capacity is lost.

Ideal for: network services, well- balanced for file server requiring performance and redundancy.

Fault tolerance: good; can tolerate one disk loss.

Array capacity: (Size of Smallest Drive) * (Number of Drives - 1)

RAID 6 (striping with two dedicated parity drives- “double parity”):

-RAID level 6 eliminates the risk of data loss if a second hard disk drive fails, while RAID array is rebuilding.

-A second set of parity is calculated, written, and distributed across all disk drives. This calculation provides a very high fault tolerance because, if two disk drives fail, there is no data loss.

- RAID 6 requires a second set of parity calculations to be made so that data from two failed drives can be rebuilt from the parity information retained on the surviving disks.

-Performance:

    

   1. Like RAID 5

   2. Fast reading

   3. Slower writing

  4. Needs hardware support

-RAID level 6 provides higher data protection to industries

-Higher data availability and tolerance default than RAID 5.

-How to avoid a second drive failure?

  1. Periodically run “verify” on the array

  2. Hot sparing with automatic rebuilds

  3. Set the rebuild priority to its highest level.

  4. Balance reliability requirements and performance expectations against the number of arrays in a single     volume.

Key factors:

Advantage: Double drive redundancy

Disadvantage: Loses two disk drives capacity

Ideal for: Mission critical

Resources:

http://www.dulcesystems.com/html/raid_description.html

http://www.answers.com/topic/raid-0

http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel1-c.html

http://www.broadberry.co.uk/explanations/RAID_level_3.htm

http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel5-c.html

http://www.3ware.com/products/pdf/raid_6_techbrief_112906.pdf

Secure Email Project

In our project Secure Email, we were asked to send a digitally signed and encrypted email. Once both emails were replied by Professor Means, we were ready to start our blog.

Please see below the screen capture of my Thunderbird inbox with both replies.

The main purpose of this project was to learn how to protect our emails that could contain sensitive data from other people other than the recipient. This is very important especially for business that share private information through emails.

In summary, the article discusses how Wells Fargo started using an easy way to have secured emails and its benefits. The vice president, Bipin Sahni, was concerned about his clients, and the security of the information that is sent online. The VP of the company emphasizes that users are not all tech savvy, thus Wells Fargo looked for encryption products, and found one very helpful.

Now having emails protected, Wells Fargo’s customers and employees send about 60,000 emails monthly.  Besides, Wells Fargo saves a lot of money in sending documents containing confidential information via priority mail to customers, and not only that, but also time.  Unquestionably, secure email plays an important role in many companies, and Wells Fargo is an example of this.

To read full article, please go to:

http://searchfinancialsecurity.techtarget.com/news/1349375/Wells-Fargo-deploys-Voltage-for-secure-email

Database Project: Microsoft Access

I would say this project has been one of the most difficult projects throughout the semester. I think I had complications working with access because this program is not very used like, Word, Excel, or PowerPoint, but it is definitely very helpful. As soon as I started working on the project, I had problems importing the table; every time I imported the table a message error came out. After several tries, I finally figured out what the problem was. I needed to change the type of the document to Excel 97-2003. See below to know what I am referring to.

Created by Ivette Franco 

Once I was done with that part, I started working on the tables, queries, forms, and reports. These steps were a little bit more challengeable, but I was able to finish it.

Created by Ivette Franco 

I learned how to add records to my table. Above, you see a table with 1002 records (users), after I added two records, one of those an “Individual” and the other one a “Family”

The query was harder than the table, especially step “2D” which took me a couple of days to figure it out. Definitely,  I think is very necessary to have a prior experience on Access in order to be able to working without any kind of complications, but since it was not my case, it took a little longer to get it done.

Step 2D solved.

Created by Ivette Franco

Basically, I had to add another Last Name field, and sorted it in ascending order. In this case, I did not check marked it, as the first one.  Then, under Left Date field I added a criteria written like this: >#9/27/2010#. This criteria would help to complete step 2D, and collect users that left the gym within the last 6 months only.  

Once I was done with the first two sections, Table and Forms, everything is a little easier. After doing this project, I can tell I have an idea of to create a Table, Query, Form, and Record.

Microsoft Office Access is definitely a good program to collect and sort data. Access not only allows you to organize your data, but to import information saved in other applications.(see figure above)

Tips:

One way to enhance the functionality of this database in “forms” is, to get rid of properties that are unnecessary, and stay with the ones that are absolutely necessary to be set. We should review form’s startup code to ensure that we are not setting any control properties that don’t need to be set. We need to keep in mind that properties assignments are very expensive in terms of performance and effectiveness. We should also minimize the number of controls on our form, loading controls is the biggest performance hit. 

Extra Credit: Avatar

To create an Avatar, I went to Doppelme.com.  This is the first time I was creating myself. Doppelme.com does not require you download anything, and it is free. Besides, it provides you many options; you select your gender, and your skin’s and eyes’ color. I was fascinated with these options.

In the next screen, you see the following options (see below) that you can use to create yourself.

                                                      Created by Ivette Franco

This part was even more fun. While I was selecting my expression, hats, etc., I noticed that there were some options that were not free, but you still have many for free. I could create my avatar very alike to myself with the free options without any problem.  I know my avatar and I still have some differences, but this was the best I could do. In order for me to create the screen capture of my avatar, I used a tool provided my computer, which is called "snipping tool", and it perfectly worked. Definitely, this was a pretty fun experience.
If you have never had a twin, go to Doppelme.com, and you will be able to create one

Tutorial 3: Social Networking, Blogs, and Wikis (Types of Websites)

I invite you to watch this video, before start explaining about the different types of websites

       Video 1      

 Creative Commons 

                                                                   

Purpose: Websites are created with many different purposes such as, commercial, educational, entertainment, informational, and so forth.

Below you will see important information about social networking, blogs, and wikis.

Social Networking:

Image 1

 

Today, “online social network” has become very common in the entire world. This type website can be also considered as web 2.0 site. Basically, social networking websites serve to connect classmates, family members, and friends. Social networking sites are being utilized to date and find partners, friends, etc.

Here is a story of a mother that found their children, after 15 years, through Facebook.

Video 2

                                                       Creative Commons

                                                                                      

These websites facilitate the communication among people. Now, instead of sending a letter to your dear friend, or to your to your uncle through the post office, it is easier and faster to just send an mail through Facebook or Twitter.

 

Created by Ivette Franco

Websites like, Facebook, Twitter, etc. enable you to let your friends know where you at, whom you are with, your status, your employer, city where you are living, share pictures and videos, and much more. Just try one these websites, and you will explore a small world in which long distances can’t impede you to express your feelings or your mood. Create your own account!

If you don't know much about Facebook, follow these steps to get started

1. Go to Facebook
2. Enter the information requested by Facebook

Created by Ivette Franco

 
3. Once you have finish step 2, click on Sign Up.    
4.Enter the weird the text you see in the "Security Check" into the text box .

Created by Ivette Franco

                                
5. Once you are done with step 4, read the Terms of Use and  Privacy Policy.
6. Click Sign Up, you are done. 

Why spending much time looking for the right man or woman?

Match.com makes it for you.  In this website, you can find different types of women and men; you just need to select the characteristics of your perfect man or women, and match.com will find you a person that matches with your preferences.  In order to be a member, you need to pay a fee. If you are single or feel alone try match.com

 Video 3

                                                      Creative Commons 

Please be advised that not all of social networking websites are free, some of them may charge you a fee for the membership.

Examples:

Image 2

Image 3

 Enjoy this video, and see how the way we communicate today has changed throughout the years

Video 4

Creative Commons

Blogs:

A blog is type of a website or part of a website. Blogs are usually upheld by a user. The user basically is in charge of making comments, or writes information about events or about any topic. These entries most of times are organized in chronological order.

Blog allows you to share commentaries or news; these may come from students, professionals, or, simply, are used as diaries by common people. Blogs can be done textually, and you can add pictures, images, music, and videos.

History: According to Evan Williams, the word “blog” means to edit one’s weblog or to post to one’s weblog.

Types: Personal, corporate and organizational, media type, devise, and many more. We can find an endless list of types of blogs.

Things in common among blogs:

• Listed in chronological order, newest on top, usually.
•  Articles are organized by category, mostly.
•  An archive of older articles
• A list of other links related to the topic
•  One or more feed backs

If you are interested in creating a blog, you are more than welcome to do so; you might have something interesting to share with us.

Please watch this video How to create a blog

 Wikis:

What is wiki?

Wiki is a webpage that can be edited and viewed by people that have access to the internet. A wiki can be a good resource of any type of information. Wiki supports hyperlinks and has simple text syntax for creating new pages and crosslinks between internal pages on the fly. Users can incorporate movies, sounds, videos, and images.  The first wiki appeared in the 90’s.

Why is wiki significant?

Wikis provide a powerful and collaborative communication tool to students and faculty.  Students can access to wikis through the internet and participate from anywhere. Wikis, also, allow faculty to get involved and participate.

Downsides:

Wikis can be modified or edited by any user, and because of this wikis are checked and revised by a group of people that are authorized to do so, and delete any inappropriate language or modify incorrect information.

This checking process demands a lot of time and requires the assistance of many people.

If you want to have more information of how a wiki works, please watch this video.

Video 5

                                                     Creative Commons

Resources:

Introduction:

Video 1:

http://www.youtube.com/watch?v=FtPb8g8Jl6I  (taken from creativecommons.org- cc)

Social networking:

http://www.webdevelopersnotes.com/basics/types_of_websites.php

Image 1:

http://www.flickr.com/photos/20493464@N00/2564571564/

Image 2:

 http://search.creativecommons.org/?q=facebook%20logo

Image 3:

http://www.flickr.com/photos/83487287@N00/3452514622/

Video 2:

http://www.youtube.com/watch?v=bKxaedI6lMc   (taken from creativecommons.org-cc)

Video 3:

http://www.youtube.com/watch?v=-z4aguu4Ex0 (taken from creativecommons.org-cc)

Video 4:

http://blip.tv/file/2088629/  (taken from creativecommons.org- cc)

Blogs:

http://en.wikipedia.org/wiki/Blog

http://codex.wordpress.org/Introduction_to_Blogging

Link:

http://blip.tv/file/1856508/ (taken from creativecommons.org- cc)

Wikis:

http://net.educause.edu/ir/library/pdf/ELI7004.pdf

Video 5:

http://www1.teachertube.com/viewVideo.php?video_id=222024  (taken from creativecommons.org-cc)
Note: There are some images created by Ivette Franco

Project WEB 2.0: "St.Jude Children's Hospital"

This project, Web 2.0, has been one of the most frustrating ones in my entire life, starting from the storyboard to putting together the information, and uploading the video. I chose scenario 3, which was for non- profit organizations; St. Jude Children’s Hospital was my topic. I decided to use Windows Movie Maker instead of Power Point Presentation. I feel very comfortable working with both of them, but I felt that Windows Movie Maker would be more useful for this situation. WMM allows you customize almost everything according to your convenience. I have always liked working with pictures and stuff, but I need to confess that the hardest part was to collect all the information with logical flow into one video, but I think patient, besides my skills, was my main tool. I learned a lot by watching videos at youtube.com, specially the storyboard. To create my storyboard I used paint, and it was mission; but paint allowed me to organize and transmit my plan. I, then, had to change the order of slides, and add a couple of slides.

I believe people don’t like to see long presentations so I made it mine short, may be a little short, but, I think, it was good enough to persuade people to donate. Since my presentation was short I could not anticipate many questions; just two which have given sense to the whole presentation. I made these questions at the beginning of the presentation in order to grab audience’s attention, and, therefore, spark curiosity. I was trying to make a longer explanation with a little history of the St. Jude Children’s hospital, but, then, I realized that that wasn’t going to cause any effect in people’s mind and attitude towards donations. I also presented some statistics about people with cancer, and I think these numbers have done some kind of impact on people’s feelings because basically that is my goal (to make audience helping this organization, St. Jude). As I previously mentioned, my presentation was short which helped me to avoid clutter. Besides, I tried to be as organized as possible, clear, and concise. In order to make my presentation readable I just placed one picture per slide, and wrote some important words, most of the information was verbally expressed. Before submitting my presentation, I revised the spelling of every word in order to avoid any typo errors (I thought I did not have any typo, but someone noticed a typo, so I then revised it , and uploaded the video again)

As Professor Means says, sometimes the best way to learn is by teaching others; and seeing people’s mistakes helps you to see your own errors. Watching someone else’s presentations facilitate me to make some revisions on my project and give me new ideas. Sometimes, it is easier to perceive others mistakes than yours. Definitely, critiquing others’ work makes you learn more.

Working on this project, WEB 2.0, has helped to become a little more knowledgeable about computers. I believe I still need to learn a lot more, but, at least, I have an idea of how to start a presentation. Definitely, you need to be creative and have the correct tools such as, microphone, computer, etc. Nowadays, presentations are playing a very important role at school and at work as well. At work, you need to be more accurate and concise. A business person needs to be able to transmit their message in a clear way through a presentation; not all positions will require you to make a presentation, but some will.

I invite you to watch my presentation: CLICK HERE

Digital Right Management - "DRM"

Before taking this class, ISM 3004, I ignored many technical words that are relevant with our daily life, especially nowadays that we deal with multimedia at school and work. Multimedia has become an indispensable tool in our lives. It is always good to be updated about technology, and have some basic knowledge. Multimedia covers a lot of topics, and among its topic there was one that attracted my attentio, DRM.

.

What is DRM?

Digital Rights Management, DRM, refers to any system that manages access to copyrighted material using technology resources. In other words, DRM restricts the free use and transfer of digital content; therefore the person in possession of digital content does not have any control over it. 

Examples: 

Image created by Ivette Franco, Copyright 2011

Image created by Ivette Franco, Copyright 2011

DRM is used…

DRM is used in different types of media, but is most frequently found in video and music consumer. The good new is we can remove DRM.

How can we remove DRM?

DRM can be removed through different software. Please see below a list of some free DRM removers:

-         Tunebite ( works with WMA, M4A, AA, M4B, M4P, WMV,  and M4V)

-         Aimersoft DRM Media Converter ( WMA, WAV, WMV, M4A, M4P, M4V, M4B, 3GP, AVI, ASF, MP4, MOV, FLV, MP3, AC3, OGG, APE )

-         Sound Taxi

 

DRM Disadvantges: 

Image 3

The major disadvantages about DRM are the several restrictions to the end user.For example,  if you buy music through your computer , you may want to be able to listen to it in you car while you are driving , or listen to it on another computer, but this may not be able to happen. Why? Because,  DRM,  most of times, is applied in a way that music can be listened through one computer only. 

You, also, may not be able to listen to the song you buy as many times as you want because it is restricted to be played a limited number of times. 

DRM Advantages:  

Online sellers are the most benefited.  DRM allows content owners to restrict the use of digital media. Besides, DRM permits content providers to keep the integrity of their copyrights.DRM is ideal to minimize piracy. 

Can we avoid DRM?

Yes, we do. If you dont want to be affected by any restriction of DRM, you can simply decide not to but any music, videos, or services that use DRM protection. 

Did you know....

Did you know that University of Florida was trying to use DRM in order to protect videos ( from the Business Program) ? Yes, they were trying to, but, so far, they have decided not to use DRM for the facility of students. 

Resources:

http://computer.howstuffworks.com/drm1.htm

http://www.wisegeek.com/what-is-drm.htm

http://www.mgtek.com/dopisp/support/kb.aspx?id=faqDRM

Image 3:
http://commons.wikimedia.org/wiki/File:DRM_Is_Killing_Music.png

Excel Project

This project was very interesting and challenging.  It was about a fitness center, in where you were supposed to help the gym’s owner in researching the effectiveness of a particular workout. Your main tool was an Excel’s spreadsheet that had data for 500 subjects. The data basically contained age, sex, and 21 heart rate measurements for a period of 20 minutes (starting from time 0:00 to time 20:00). Once, that we had an idea of what the project was about, it was time to start formatting and manipulating the data. First, we were asked to name the spreadsheet “Raw Data” and make the first 2 rows bold, and center the gender column.  So far, everything was pretty easy because it was basic stuff that we learn in middle school. But, when I was asked to use the “Freeze Panes” to lock the first 2 rows, I got stuck; this step required me to do a little bit of research to figure it out. I believe this feature is very useful, mostly when you want to print out balances, data, and so on. After I finished formatting the raw data, it was time for me to start working with formulas. 

This part of the project made me recall when I was a middle school student. It was time to refresh my memory and start working on the formulas. The first formula was easy; we were asked to figure out the “maximum heart rate”.  Then, we needed to figure out the “Target Rate”; for this step I applied the first formula and multiply it by the percentage given. This step was easy as well.  Next step, figure out “Target Achieved”, was a little more difficult to interpret. The formula itself was simple, but I took me a while to understand the question .In this case, I applied my analytical skills. Once, I understood the question, I went over my Scavenger Excel assignment to solve this step. Determining the” Heart Rate Increase” was simple because we were given a hint. We, basically, needed to change the number to percentage. After I finished with the manipulation, I formatted the spreadsheet so when I print it out; it came out in a certain way. I added some headers and footers (to the right and left). I also changed size of the text. Basically, steps mentioned above pertained to the easy section.

The challenging part started with the pivot tables (See figure). In order for me to solve the last steps, I had to watch some videos, which were very helpful. In the past, I had not used pivot table for anything, but I believe this feature of excel could be very useful. Excel and Word are software that I have with for many years, but I have realized that I still don’t know some features of these ones. Doing this project has helped me to become a little more knowledgeable of Excel.  During this project, I learned analytical skills that help to interpret the situation or problem very well; problem- solving skills; technical skills which are very useful in business; organizational skills; and computer skills.

Tutorial 1: Cache "cash" Memory

1. What is cache memory?

Cache memory  (also called buffer memory) is a memory that bridges the random-access memory (RAM) and central processing unit (CPU).  Cache memory is quicker than main memory (RAM) and, allows instructions executed and data to be read and written at higher speed.  Basically, cache memory is a small amount of high- speed memory.

Cache Types: 

a. Reading using  cache:

               

    I.  Look Through: Central processing unit (CPU) requests memory from the cache. Only if the data is not present is the main memory queried.

   II.  Look Aside: Central processing unit (CPU) requests memory from cache and main memory simultaneously. If the data is in the cache then it is returned, otherwise the CPU waits for the data from the main memory.

b. Writing using cache:

                 

    I.  Write Through: When data is stored back to memory it is written to the and main memory at the same time.

              

   II. Write Back: Data in the cache is compared to the data in the main memory. Data is written only if there is a difference.

See diagram below:

2. Where is cache memory placed?

Cache is placed between the central processing unit (CPU) and random access memory (RAM).

3. What is the difference between cache memory and main memory (RAM)?

Main memory (RAM) is used to store graphics, pictures, data, programs, etc. Basically, main memory is a general purpose memory.  Cache memory, however, is a specialized memory. Cache memory is used by the CPU to store data temporarily and speed up access to the main memory (RAM).

Why is important cache memory?

Cache memory plays a very important role in computers' performance. A CPU without cache memory would operate at very slow speed receiving instructions directly from them RAM. In other words, CPU productivity would be reduced by (18/ 0.3= 60) times. 

Cache Levels:

•  Level 1 (L1):  Usually built onto the microprocessor itself . It has two parts: instruction cache and data cache. Instruction cache contains instructions from the RAM that have been decoded, while data cache contains data from the RAM that has been recently used during CPU operations. 
• Level 2 (L2): Used to be located on the motherboard, but now it resides on a separate chip next to the CPU. L2 is slower  and bigger than L1.

• Level 3 (L3):  It is slower and bigger than L2.

All these levels of cache mentioned above serve to reduce the latency time when transferring or processing information.  

Note:

Cache that is built into the CPU is faster than separate cache, running at the speed of the microprocessor itself. However, separate cache is still roughly twice as fast as Random Access Memory (RAM).

For more information, please watch video below:

 

References: 
http://computer.yourdictionary.com/cache 

http://www.sqa.org.uk/e-learning/CompArch02CD/images/pic009.jpg
factoidz.com/cache-memory/
http://www.build-gaming-computer-guide.com/importance-of-a-cache.html 
http://www.sqa.org.uk/e-learning/CompArch02CD/images/pic009.jpg
http://en.kioskea.net/contents/pc/processeur.php3