RAID and “Hot Swappable” Drives

Posted on April 19, 2011 by David Rier

In previous posts, I’ve introduced the concept of RAID and how it can help to safeguard your data.  There can be one “fly in the ointment” related to a RAID implementation.  That problem is the time that is needed to recover your data from a “crash”.  Depending on the size of the drive arrays involved, the recovery process can take many hours.

(I can hear some of you say: “As long as I get my data back, I don’t care if it takes a number of hours”.  If that’s true in your situation, then a RAID-and-backup implementation should give you peace of mind.)

If you cannot afford to wait hours to have access to data on a damaged array, there is still hope.  Some servers support what are called “hot swappable” drives.  These are drives that can be taken out and replaced (I.e. swapped) while the server is turned on.

In a hot swappable implementation of a RAID, a damaged drive can be swapped with an empty replacement drive without turning off the server.  The server will detect the swap and immediately start the process of rebuilding the array.  While there may be some slowing of the server response while the array is being rebuilt, the data is still available during the process.

Notes:

  1. All of the above requires planning before you even buy your server.  You have to make sure that:
    1. You buy the right number of drives (including a replacement unit) based on the RAID you implement,
    2. All the drives are of the same size,
    3. The drives can be use for hot swapping, and
    4. The server and drive controller can support hot swapping.
    5. In some systems, it is even possible to have your replacement drive already installed in the server.  It is only used when the system detects a crash of one of the other drives.  The system then uses the “spare” drive to immediately and automatically rebuild the array.
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MicroGoose

Posted on April 15, 2011 by David Rier

One summer weekend, the air conditioning unit for our server room “died”.  When we came in on Monday morning, the temperature in the server room was over 110 degrees!  By sheer luck, we did not lose any of our hardware to thermal damage – a potential loss of over $50,000.

I immediately looked for a way to monitor the environmental conditions of our server room.  It had to have a couple of requirements.  First, it had to be inexpensive.  Second, it had to have a way to notify me if there was a “problem”.

What I located was a product called the MicroGoose from a company called ITWatchDogs.  The product page is http://www.itwatchdogs.com/product-detail-microgoose-9.html.  The list price of the unit is $199.

The MicroGoose is a small unit that attaches to our network.  It resides in our server room and monitors the temperature and humidity.  It was simple to set up and allowed me to define my own “alarm” conditions.  If the temperature or humidity numbers exceed safe levels that I define, the unit sends an email to me (which is then relayed to my BlackBerry).

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Common RAID Strategies

Posted on April 5, 2011 by David Rier

There are two common ways to implement RAID on your PC or server. They are called RAID 1 and RAID 5.

RAID 1:

RAID 1 is sometimes called “mirroring”.  It is more commonly used on PCs than servers.  The drives that you have are split into two equal groups.  Your data is written to both halves of your hard drive storage at the same time.  In other words, you have an immediate copy of your data in two separate (and equal) locations.

The only down side to RAID 1 is that your overall data storage on your server or PC is cut in half.  However, your data is well protected.  If either of your data storage locations suffers a non-recoverable problem, you just replace the damaged storage and the system will rebuild the “mirror”.

RAID 5:

RAID 5 is sometimes called “striping with parity”.  It is more commonly used on servers.  It requires that you have 3 or more identical drives that are set up into a storage array.  Data is written across all but one of the drives.  The last drive contains parity (or checksum) information.

To explain how RAID 5 works, let’s consider a simple storage array of 3 drives.  We’ll call the drives A, B and C.  In our simple example, data is written in stripes on drives A and B and drive C contains the parity information.  Like a simple Algebra equation, the parity information works in a way that is analogous to A + B = C.  If any of the drives is damaged, it can be replaced and the system can restore the information that was missing from the array based on how the parity information is calculated.

Notes:

  1. I have deliberately simplified how the RAID systems are actually implemented.  However, you should be able to see how both systems help to make your data safer.
  2. Although implementing a RAID increases the safety of your data, it is not a replacement for backups. Remember to backup your data regularly!
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RAID – Protect Your Data

Posted on March 29, 2011 by David Rier

It’s always a good idea to protect your computer-based data.  The first line of defense for data protection is backing up your data.  See my earlier posts (http://www.davidrier.com/wp-admin/post.php?action=edit&post=121 and http://www.davidrier.com/wp-admin/post.php?action=edit&post=123 ) for advice in that area.

Another way to protect your data is to set up your computer so that the hardware itself helps to protect the data.  This tip requires that you have two or more hard drives on your system.  As a result, it is usually used on servers.

Set up your system to use a RAID (a Redundant Array of Independent Drives).  Since hard drives are getting bigger and less expensive over time, this should afford you some data protection without stretching your budget too far.

In further posts, I’ll go over the different types of RAIDs that you can set up and what dvantages they offer to you.

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Have a Backup Active Directory (AD) on Your Windows Network

Posted on March 22, 2011 by David Rier

If your have a Windows network in your business, it is most likely that it is set with an Active Directory (AD).  The AD keeps track of all the devices and users on your network.  It also acts as the main “traffic cop” for your network – authenticating users and keeping track of their rights on your network.

That is a critical function on your network!  If that electronic traffic cop is not “on the job”, unauthorized users could enter your system or users can enter data files for which they do not have permissions.

What would happen if the sole AD of a network got damaged?  You would not be able enter the network or use devices attached to the network.  Would that be a problem? — You bet!

So how do you safeguard yourself?  Set up a backup AD on your network. Your secondary AD keeps in touch with the primary one.  If the primary AD is damaged or is not working, the secondary (or backup) AD will take over the primary AD’s functions while you work to restore the damaged one.  This will allow you to use your network, its devices and data without being shut down by the loss of a sole AD.

A word to the wise should be sufficient.

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Personalize Your Browser

Posted on March 16, 2011 by David Rier

If you’re like me, you spend a fair amount of time on the Internet.  As I have said before, my default browser is Mozilla Firefox.

One of the reasons that I prefer Firefox is that it allows me to personalize the software so that I can use it more efficiently.  Two areas particularly help me to get more work and research done while I’m surfing:

1.      Bookmarks – Bookmarks capture the address of web pages.  I can organize them and use them to quickly navigate to useful pages I need in my job or for personal use.

2.      Add-Ons – Add-Ons allow me to add extra functionality to my browser.  As an example, I can have my email accounts constantly monitored for new messages or I can be notified when an item is available at a lower price elsewhere in the Internet.

Poke around in your browser.  Test how you can personalize it with the tools that are available to you.  It will make your browsing experience faster, more efficient and more enjoyable,

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Where Was I? – Bookmarks and Favorites

Posted on March 9, 2011 by David Rier

Browser software lets you surf the Internet to your heart’s content.  Whether by design or accident, you will run into pages that warrant a second look and/or are useful both now and in the future.

You don’t have to mentally remember the page’s full web address to get back to the page in question.  As well, you don’t have to duplicate the series of searches that eventually yielded the page.

Instead, use a bookmark (or favorite) to capture the full address of the useful page.  Each browser has its own icon or steps that allow you to capture a page’s address and put it into a list for later use.  Take the time to learn how to use your browser for saving and organizing bookmarks.  You will build a list of useful sites and become a more proficient user of the Internet.

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Faster Internet Searches with Metasearch

Posted on March 1, 2011 by David Rier

The Internet is (potentially) a source of lots of information and content.  However, you need to look around (I.e. search) for sites that meet your needs and/or answer your questions.

Google is not the only search engine out there.  There are lots of competing engines – Yahoo and Bing are just two of them.  Since each engine builds its own listings of what is in the Internet, a search on one engine will return different results than the same search on another engine.

One way to speed up your searches is to use what is known as a metasearch engine.  Such a search engine allows you to enter a search term once.  The identical search is then submitted to a number of different search engines at the same time and the aggregated results are returned to you.

Wikipedia provides a list of metasearch engines (https://secure.wikimedia.org/wikipedia/en/wiki/List_of_search_engines#Metasearch_engines).  My favorite is Dogpile (www.dogpile.com).  It submits searches to Google, Yahoo, Bing, Ask.com, About.com and others.  Ignore the weird name and give it a try.  I think you’ll find it very useful.

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Searching on the Internet – Making It More Exact

Posted on February 22, 2011 by David Rier

The Internet is a vast collection of information, files etc. that is growing almost exponentially.  With so much available, how do you find what you are looking for?

Here are a couple of suggestions for how you came make your searching more useful and exact:

1.      Be as specific as you can in your search terms.

2.      Use “advanced” search options to narrow down your searches even more.

When you are more specific in your search terms, you usually add more words to the “search terms” box.  As an example, here are some recent search results from Google about upgrading your computer memory:

Search Term(s): Number of Results:
Computer 652,000,000
Computer Memory 30,200,000
Computer Memory Upgrade 4,270,000

As you add more words to your search terms to make them more specific, the number of results is greatly reduced.  If you then take advantage of “advanced” search options such as choosing only videos (to see how upgrades are done), the last upgrade term returns only 2,180 results!

There are many other “advanced” options that you can use to zero in on the results that are most useful to you.  You can ask for results only in a certain language, only within a certain date range, only from a blog, etc.  Take advantage of the search tools available to you and you will get to the useful information on the Internet.

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Protect Your Identity

Posted on February 15, 2011 by David Rier

Identity theft is a hot topic in just about every form of media.  The horror stories related to identity thefts almost make you want to swear off using the Internet and all electronic devices.

Let’s be honest, there are criminals out there that want to steal people’s identities and plunder their financial accounts.  They are working 24×7 to try to separate you from your money.  Visiting a “bad” web site, a moment of inattention in your email box, not shredding your financial documents, etc. can open you up to a long, painful process of recovering from identity theft.

You pay for car, medical or home insurance to make sure that you are not too damaged by bad things that might happen in your life.  Why not get a form of “identity theft insurance”?

I personally use the ProtectMyID service (www.protectmyid.com).  It is run by Experian, which is one of the three major credit reporting services in the US.  It provides you with constant monitoring of your accounts and works with you to protect you from identity theft.  If your identity is stolen, it also helps you to recover from such an unfortunate occurrence.

Do yourself a favor and at least check out the web site.  It’s worth the cost.

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