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12
Jul
2010

RAID Simplified

by Administrator

If you’re a webmaster or someone that has ever dealt with a server, you have probably heard the term RAID. RAID, which stands for Redundant Array of Inexpensive Disks, or occasionally Redundant Array of Independent Disks, is a way to put 2 or more hard drives together in different configurations to meet certain criteria, for better redundancy, faster speeds or both. While there are many sites on the internet that explain RAID already, many of them are quite technical in nature so this explanation will simplify it by describing each RAID type, what is required and the pros and cons of each. There are actually 13 different RAID types but only 4 that are commonly used. I will cover these 4 in detail.

RAID 0: RAID 0 is sometimes called striping. RAID 0 requires at least 2 drives. Data is written sequentially to all drives, which means that the pieces of a file will be written across all the drives. Because of this, this file can be read from the drives much faster as the reads come from all the drives simultaneously. A RAID 0 works well for a server where increased disk space is desired but redundancy is not an issue. RAID 0 may be used for file servers where a backup file server is also in place in case of data loss.

Pros:

  • Easy to create
  • Fast reads and writes
  • Can be done with only 2 drives
  • Disk capacity is the combined size of the drives (ie, 2 200 GB drives would give you 400 GB of capacity

Cons:

  • No redundancy. If any drive in the RAID set fails, you lose all the data on that drive
  • Not a true “RAID” due to the lack of redundancy (remember, RAID stands for “Redundant Array of Inexpensive Disks”)

 

RAID 1: RAID 1 is mirroring and requires a minimum of 2 drives and the drives must be installed in pairs (2, 4, 6, etc). Each 2 drives is a mirror of each other where all data on each drive is identical to its pair. RAID 1 is perfect for a web server where 95% of the disk access is read from the drive to deliver web content and the other 5% is FTP uploads where speed isn’t really an issue. By default, every managed server that NationalNet builds comes with RAID 1 (for speed and redundancy) unless otherwise specified by the customer, or the server is a database or some other type of specialized server that requires a different type of RAID.

Pros:

  • Twice the read speed of a single drive
  • Perfect for a web server where most of the activity is reads from the disk
  • True redundancy in that if a drive fails, you just replace it and the RAID automatically rebuilds

Cons:

  • Slower writes than a typical RAID
  • The capacity is that of the single disk (ie, 2 200 GB drives in a RAID 1 give you 200 GB of capacity)

 

RAID 5: RAID 5 requires at least 3 drives. The data is written to all drives with sections of the drives dedicated to the parity bits. Without getting too technical, the best way to explain parity bits is that they are in charge of ensuring data written to the disk is correct and not corrupted. Because of the way the data and parity bits are written to all three drives, each drive can fill in for any other failed drive. The capacity of a RAID 5 is N-1 (ie, you lose one drive to the RAID), which means that if you have 4 500 GB drives, your capacity would be 1500 GB. RAID 5 works well where more disk space is required than what can be had with a single drive.

Pros:

  • Highest READ speed of all RAID
  • Good disk speed
  • Good redundancy

Cons:

  • Disk failure can impact performance
  • Slower write speeds
  • Expensive to implement. Requires at least 3 matching drives and an expensive RAID card

 

RAID 10: RAID 10 is two mirrored drives (see RAID 1) striped together (see RAID 0). It requires a minimum of 4 drives to implement and like both RAID 0 and RAID 1, must be done in pairs. RAID 10 is very fast for both reads and writes and works well for servers that require high availability as well as fast read and write disk speeds. A database server would be a good example where you would implement RAID 10.

Pros:

  • Very high disk speeds for both read and write access
  • Given a 4 disk RAID 10, you could lose two drives and not lose any data provided it was one drive from each RAID 1 set in the RAID 10. Given this same 4 disk RAID 10, the failure of one drive would never affect the data

Cons:<

  • Expensive to implement. Requires 4 drives and an expensive RAID card
  • Limited scalability

 

These are the 4 most often used RAID types. Here is a condensed list of the other, lesser used, RAID types. These RAID types are rarely used due to the fact that the disadvantages outweigh the advantages or due to cost constraints or both.

RAID 0+1: Similar to RAID 10 in that it’s a mirror/striping combination but without any redundancy. Any single drive failure causes total loss of data on the failed drive.

RAID 2: Requires expensive specialized disks and uses ECC code. Rarely if ever used.

RAID 3: Uses parallel disk writing method. Requires a minimum of 3 drives and uses 1 drive dedicated to the parity bit (see RAID 5). Very slow after disk failure and does not use disk space very efficiently (lots of wasted disk space)

RAID 4: Independent data disks with one disk dedicated to parity bit. Requires minimum of 3 drives. Very slow disk writes. Difficult to rebuild after a failure.

RAID 6: Very similar to RAID 5 only with a second set of parity bits written, which gives it higher fault tolerance in a mission critical situation. Very complex to implement and very poor write performance. Requires a minimum of 4 drives due to the extra parity bit.

RAID 7: Unlike the other RAID levels, RAID 7 isn’t an open industry standard; it is really a trademarked marketing term of Storage Computer Corporation, used to describe their proprietary RAID design. RAID 7 is based on concepts used in RAID levels 3 and 4, but greatly enhanced to address some of the limitations of those levels

RAID 1E: Simply put, RAID 1E is variation of RAID 10 only with more implementation headaches and less redundancy

RAID 50: Without getting too technical, a RAID 50 is similar to putting a RAID 5 and a RAID 0 together. Better redundancy but a high level of complication to implement and maintain

RAID 53: Very similar to a RAID 5 and RAID 3 put together.

Hopefully, you found this information helpful and maybe, just maybe…when you’re selecting your web hosting company and they ask you if you need RAID, you’ll now be able to hold your own in that part of the conversation.

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25
Jun
2010

10 Tips to Selecting Your Webhosting Company

by Administrator

You have your business plan. You’re working on your web site. You have all the pieces and it’s now time to select a web host. You go to Google.com, and after a bit of searching, you find a myriad of hosts all promising the same thing. How in the world can you make sense of all of the choices, select a host that is dependable enough to keep you running and not kill your business before it even gets started? To help you in your quest for a dependable host, here are the 10 best tips we can give you.

1. Determine Your Needs. Does your web site have particular software requirements that only certain servers or hosting companies can provide? For instance, if you’re doing live streaming then you need to make sure that the hosting company can support live streaming. Your business model may be such that you require 100 email addresses and auto responders, but the host you’re looking at may only allow 50 emails. You may require 10 GB of disk space but the plan that you’ve selected only allows for 5 GB. Itemize your needs on paper before starting your research into web hosting companies and narrow your search based on your particular needs.

2. Shared, Managed Dedicated or Unmanaged Dedicated Now that you have determined your requirements, you need to decide if you need a shared account, managed dedicated or unmanaged dedicated server. Start by going to your list in tip 1. The amount of traffic you expect as well as the disk space required will help you decide. In the beginning, a shared account may be perfect for your needs and can be obtained for as little as $2-3 per month. However, a shared account may come with limitations – you may not be allowed to have databases or certain software programs. Also, when you share a server with other customers, there is always the possibility that other customer web sites could affect the performance or security of your site. Should you decide on shared hosting, make sure the company also offers dedicated servers. Planning for growth can determine which hosting company to chose, so that you’re adequately prepared to move into a dedicated hosting plan when the time is right, and still remain with the same hosting provider. If you require strong security or want the peace of mind in knowing that other customers cannot affect you, then a dedicated server is the way to go. Of course, a dedicated server comes at a much higher price. Bargain dedicated servers can be found for as little $49/month, but beware, because the old adage that “you get what you pay for” is certainly true here. If you decide on a dedicated server, then you have another decision to make – managed or unmanaged. With an unmanaged server you are given full control of the server and will be required to set up any software needed for your site as well as ensuring the server is secure. You may decide that you need a control panel to make server management easier or may determine that your skill set is such that you can do all of your work from the command line. If you decide that a fully-managed server is the way to go, you have an entirely different set of concerns. Many hosts tout their servers as “fully-managed” yet they give you a control panel so that you can do most functions yourself. Their idea of fully-managed is to manage the hardware and operating system updates and maybe provide cursory assistance with minor problems as they arise. Other hosts, NationalNet included, take care of everything for you except your web site and become virtual employees of yours, but of course, this comes at a higher price. To avoid surprises later, be sure to ask questions about what level of support comes with their fully-managed servers.

3. Windows or Linux? The large majority of web hosting plans are built around some version of Linux (CentOS, Redhat, Debian, etc). This is usually not a concern but you should make sure that the hosting plan you have selected comes with an operating system that will support your web site. If you have created your web site in .asp or .NET then you’re going to need a Windows server. Make sure that your “needs” list from tip number 1 includes the operating system and that you select the correct hosting package based on that.

4. Investigate Their Support No matter what type of plan you select, be it shared or dedicated, managed or unmanaged, at some point you’re going to require support. Support is an area you never think about until you need it, and when you do need it, you want it to be fast and effective. As mentioned above, take the time in the pre-sales process to ask questions. What is included with the support? What is the average turn-around time for resolution of issues? What is the process for obtaining support? How many tech support people do they employ? If the host says they have 24/7 support, then call it at 2 AM one morning and confirm. Many hosts that claim 24/7 support in fact use an answering service that cannot do anything for you other than take down your information and then call someone and wake him or her up, thus delaying your support request.

5. Beware of Hosting Review Sites There are literally dozens of hosting review sites on the internet and unfortunately, it’s very difficult to take any of them seriously, mainly because they are all supported by advertising from hosting companies. Just because a web hosting site is listed on a review site and has good reviews from the site does not guarantee that the host is any good. Of course, there are exceptions to every rule and there may be some legitimate review sites, but by and large you should take them with a grain of salt.

6. Location, Location, Location There is another type of webhosting other than shared, unmanaged and managed – colocation. Colocation is where you own your equipment and you rent space from a hosting company. The company provides you with a place to rack your equipment as well as power for the equipment. Optionally, they may also supply you with bandwidth or you may purchase this separately if the data center is carrier neutral. If you’re doing colocation, then location of the data center may be important to you, especially if you wish to personally deal with your equipment. Pick a data center too far away and you’ll be regretting it when you have to do that 2 AM drive to resolve an issue. Most colocation/data centers offer “remote hands” where you instruct them on what you wish to have done. Should you require remote hands, and it’s a guarantee that you may at some point, make sure that the techs are capable. Some data centers use the security guards or other non-tech savvy personnel for remote hands which will certainly delay the resolving of any issues you have. If the remote hands are provided by very qualified technicians then proximity may not be an issue for you.

7. Investigate the Performance and Reliability of Their Network Web site owners at the very least want two things – a site that is fast and a site that is always up. When selecting a host, you should take the time to look at their network. Find out if they have redundancy in their network equipment. If they only have one router and it fails, your site is going to be down until they get it repaired. A good host will have multiple upstream bandwidth providers to protect against the failure of a provider, as well as having the ability to use multiple providers to route around Internet trouble spots. Ask the hosting company to provide you with a test file and a few sites that they host so you can check the speed of their network. Be sure to check all the sites they give you because there is always the possibility that a site is slow through no fault of the host. Don’t hesitate to ask questions about their network including number of providers, type of network equipment and the configuration of it. A properly set up host will be proud to discuss this with you.

8. Ask About Their Other Offerings While most hosts will provide basic hosting services as well as email accounts and maybe backups, there are other services and offerings that may help you make your decision. While you may not require these services in the beginning, you might find yourself wanting them in the future. Some services to consider are backups, business class email, web statistics, support for mobile devices, shopping cart software, content delivery networks (CDN) and cloud storage.

9. Phone A Friend You wouldn’t hesitate to ask a friend about a restaurant or where you can find a good mechanic, so use that same approach here. However, while everyone eats and most people have a car, it may be a bit more difficult to find a friend that actually hosts a web site. The good news is that you’re in luck – there are many forums on the Internet so with a bit of searching you should be able to find one that is frequented by webmasters. Ask around but be aware that many posters are also paid by hosting companies to shill for them. There are also many industry-specific forums so it’s quite likely that you can find a forum full of webmasters running sites similar to yours. Not only will you find good hosts, but you’ll also learn who your competition is.

10. Don’t Make Assumptions/Buyer Beware It’s been said a couple of times before but it bears repeating; ASK QUESTIONS. Don’t assume that because all the other hosts you are looking at provide backups that the one you’re thinking of selecting does. Beware of claims like unlimited bandwidth or unlimited disk space as these always come with some sort of disclaimer, so be sure to read the fine print. Ask them about their Service Level Agreement (SLA) as well as their terms of service. Ask to see a copy of the contract or Master Service Agreement (MSA) as well as any other document you may be asked to sign. Don’t be afraid to have a lawyer read all of the documentation to prevent any “gotchas” later.

 

Hopefully this list, while not all-inclusive, has enough information to help you make the right decisions when selecting a web host for your brand new web site.

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16
Apr
2010

So, Just How DO I Stream Video On My Website?

by Administrator

Streaming Video IconWe’ve all watched videos on the internet, but what is it that you really need in order to put videos on your website?

Lets start by explaining the difference between the two prevalent ways to serve up video – streaming video and HTTP download video (there is also “progressive downloading” which is a hybrid of streaming and HTTP download, but I see no compelling reason to use or discuss it).

HTTP download requires you to download a fair amount of the video before it will start playing and in some instances depending on the video format, the entire video has to be downloaded before it will play. HTTP download will generally have a certain amount of buffering even on a high-speed internet connection. With HTTP download, the video player can’t fast-forward to parts of the video that haven’t been downloaded yet. We’ve all seen the buffering bar when watching a video (The darker grey line that shows you how much you’ve actually downloaded). Without streaming you can skip ahead in that grey line, but if you go past the end of the grey line, you are forced to wait for the download to catch up. Like most people, including your surfers, I don’t like waiting.

 

Streaming video gives you the ability to view a video starting at a point other than at the beginning as well as skipping around in the video without having to wait. Streaming video will also start playing much faster, usually almost immediately. The obvious advantage is the lack of waiting required to view a video. Another advantage to streaming is the ability to stream live events, or webcast. So, given the obvious advantages to streaming video, we’re going to focus on that in this article

There are three components to streaming a video. First, you must have a server deliver the video. Next, there is the player that receives the video and displays it to the viewer and, of course, you have the video itself. All three of these components need to be set up properly in order to stream the video.

So let’s start with video formats. They are, in no particular order:

     

  1. Windows Media Video
  2. RealMedia
  3. Quicktime
  4. Adobe Flash
  5. H.264

 

Windows Media Video
Advantages:

  • Good compression and quality
  • Wide compatibility with Windows PCs

Disadvantages:

  • Certain older versions of Windows Media Player may experience playback issues
  • Not widely compatible with Mac and Linux
  • WMV doesn’t support user interactivity well

Top

 

 

RealMedia:
Advantages:

  • None that I can think of

Disadvantages:

  • Hardly anyone uses RealPlayer anymore, so you would have a very limited audience.

Top

 

Quicktime:
Advantages:

  • Excellent compression and quality
  • Compatible with all Macs and many PCs

Disadvantages:

  • Cannot contain interactive objects like buttons and textboxes
  • Quicktime Player is not installed by default on PCs

Top

 

Adobe Flash:
Advantages:

  • High Quality
  • Can contain interactive objects
  • Smaller file sizes
  • Most computers have the flash plugin by default

Disadvantages:

  • SWF files are limited to 16,000 frames

Top

 

H.264:
Advantages:

  • Higher quality with smaller file size due to compression

Disadvantages:

  • End user must have Flash Player 9 or higher (which the majority do)

Top

 

The leading contender of video formats currently is flash video (although H.264 is quickly overtaking Flash due to the DVD level quality it can display). The main reason is that the files it creates are smaller then many of the other video codecs like mpeg or divx. It also supports indexing. Indexing is putting fixed points in the video during the encoding process so you can skip around. This is required for streaming so you actually have a place to start later in the file. Some common tools for encoding a file to flash video are ffmpeg and mencoder (both free). Flvtool2 is usually used to add the indexes after the flash file is created. National Net supports all of these tools and can install them at your request. You can also use on2 which is a company that will encode videos for you or a product like Sony Vegas, which is PC based software that allows you to encode your own videos.

Next comes the server. There are two main protocols for delivering the video. HTTP, which is the traditional delivery method of the internet (if you have a website, you’re using HTTP already) and RTMP which was designed specifically for streaming videos. Both are valid ways to stream, but the difference is that HTTP is usually free while RTMP software tends to be more commercialized and sold by companies like Adobe. Some people claim that the RTMP servers function better but I’m not sure I agree. HTTP servers include apache, nginx and lighttpd. They all require that specific modules be installed in order to read the indexes in the file. Wowza and Adobe Flash Server are just two of many choices for setting up an RMTP server. National Net supports all of these servers as well.

Last we have the players themselves. Web pages, despite our best efforts are still primarily static places. One of the few technologies to come out that allows us to interact dynamically in a web page is shockwave flash. It was making flash be able to play video that gave us the players we see today. Once you embed the flash file in your web page, it becomes a video player and most of them understand how to stream a video. This allows you to skip ahead and watch videos until your heart’s content. A few popular players are jwplayer , flvplayer , flowplayer and Adobe’s own flash player. These are all embedded in your pages and the web browser runs them. Setting up the flash player in your web site is not extremely difficult and each of the players mentioned above come with adequate documentation to assist you in setting up the player in your web site.

Remember, if you don’t like waiting for a movie to play, neither do your surfers, so do them a favor and always be sure to use streaming videos where possible.

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29
Mar
2010

How Secure Are You? Tips for Better PC Security

by Administrator

How Secure Are You? Tips For better PC security

The internet is arguably one of the greatest inventions of all time. Literally millions of web sites exist for the purpose of research, entertainment, news and information, socializing and everything in between. It’s made the world a smaller place, and while some might argue the fact, I think a better place. In fact, it’s hard to imagine a time when we didn’t have the internet at our fingertips.

According to the Internet World Stats that collects its data from Nielson//NetRatings and the International Telecommunications Union (ITU) as of August 2009 there are 1,733,993,740 people on the Internet world-wide and 227,719,000 people in the United States on the Internet with that number increasing daily. With the boom of the internet, there has been a boom in the number of hackers and bad guys looking for ways to exploit the internet for various reasons. Some hack for profit by taking over web sites and redirecting the traffic. Some create phishing sites to try to steal your identity or credit card information while some hackers hack just for the challenge and the thrill of it. What this means to you is that you have to always be vigilant in your cyber-travels. This article will try to educate you on what you should be on the lookout for and things you can do to ensure you don’t become a victim to these “ne’er do wells” out there.

In today’s article, we’re going to examine this from the desktop level. A future article will examine server security, so stay tuned.

 

Phishing, Spam and other Email Scams

One of the most prevalent hacker schemes is called phishing (pronounced “fishing”). In a phishing scam a hacker will create a copy of a well known site, such as a bank, BestBuy, Ebay or PayPal…it could be any site that takes credit cards or contains credit card or other personal/sensitive information. Once they have created this fake and very authentic looking site, they will send out a mass email that appears to come from that site. That email will try to convince you to either enter your username and password or credit card information under the guise of “we’re updating our records”, “you’ve won a contest” or “there has been a security breach and we need to verify your information to ensure your safety”. Be aware that the real company would never ask you to divulge that information. Should you receive an email like this and you have doubts about its authenticity, you should contact the company via phone to confirm, but under no circumstances should you enter your username/password or any other sensitive information into a web site that you have clicked a link in an email to get to unless you are absolutely sure of the emails origin.

Another prevalent scam is called the 419 or Nigerian scam. This is a variation of the old “Spanish prisoner” scam. The way this works is that you’ll be contacted by someone you never heard of who claims that you either inherited a large sum of money or that this person has a large sum of money to move out of their country and requires your assistance. In exchange for your assistance, they will give you a large cut of this sum of money. Of course, “your assistance” is in paying the scammer a sum of money up front to assist the scammer in getting the money out of the country (claiming he has to bribe officials, pay for transport, etc). The bottom line is that if you are legitimately owed money, you will be contacted via more traditional methods such as a certified letter. Never trust an email from someone promising you a large fortune. The old adage of “if it sounds too good to be true, it probably is” holds true here

PC Security

PC security starts with one of the most simple but often overlooked aspects – a password. I am always surprised at the number of people with a PC that have no password required to log into it. What I usually hear is “I’m the only one that ever uses this PC”…but that couldn’t be further from the truth. If your PC doesn’t have a password, I can almost guarantee that you are NOT the only person using it – you just think you are. The easiest computer in the world to hack is one without a password. Hackers will easily gain access to your PC and use it for all sorts of evil, such as using it to attack web sites or other computers, spreading viruses, sending out spam and more. ALWAYS…ALWAYS (did I mention ALWAYS?) have a password for your PC…the stronger the better. So, what is a strong password and how do you make a strong password? I’m glad you asked. First, it should never be a name or a dictionary word. Hackers use scripts called brute force scripts to try to guess passwords. A brute force script will try literally thousands of username/password combinations from a database to see if one works and if your password is “abcd1234″ I can guarantee you this script will find it, so you might as well not even have a password. You should always use a combination of UPPER case and lower case letters as well as numbers and special characters. One good way to create a very strong password but is easy to remember is to take a 7-8 word phrase (or two shorter phrases) and use the first character from each phrase. Capitalize the first four letters then add one special character to the end. So, for example “how much is that doggy in the window” could be “HMITditw?” No one would ever guess that password but you would easily remember it. You can also substitute numbers and characters for letters – @ could be “a”, $ could be “S”, 3 could be “E” and so on.

Also, don’t write your password and stick it to the bottom of your keyboard. If I were a hacker (fellow office worker, “friend”, etc) who somehow gained physical access to your PC, the FIRST place I would look would be for a postit note with your password on it.

Next, protect your PC from viruses. Make sure you have virus protection installed. AVG offers a free version that has actually worked quite well for me and checks your email and downloads for potential viruses. It also automatically updates itself with the latest virus library. Norton and McAfee are two other companies that offer protection software but there is a fee associated with their products.

Because email is the one application where your permission is not required to send you something, it is the most abused application on your PC. Of course, it’s also the one application you really cannot live without. So, here are some basic rules to help protect your email.

1. Never open an attachment from a sender you do not know. Attachments can contain viruses and all sorts of bad things.

2. You should have at least two email addresses. One that is private for friends, family and business associates. Instruct them to never give this email to anyone. The second one would be used for things that you purchase online or forms you fill out. This allows you to do a couple of things. First, if you receive an email to your “private” email, you can trust it more. Secondly, you can set up more aggressive spam filtering on the secondary email.

3. Never put sensitive information (passwords, credit card numbers, etc) in an email as email is not encrypted and can be intercepted as well. Should you need to provide this information to someone, it’s best to use the old-fashioned method and call them on the phone. Think of it as sending a postcard written in pencil. As the card is delivered it makes numerous stops and can be altered or read by various people.

4. Never reply to a spam email, even to “unsubscribe”. Any sort of response acknowledges that the email address is legitimate and you open yourself up to additional spam. Simply hit the delete button – it takes less than 1 second to hit that delete button.

5. Just like your PC password, always create a strong password for your email accounts.

PC security requires some basic steps and some basic common sense. You lock your house at night and when you leave. You lock your car when you go into the store. Be sure to do everything you can to “lock your PC” and you greatly increase your chances of not falling prey to the hackers of the world.

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