Raid data recovery is somehow different from all other types of data recovery. Most experts advise not to try to recover the data yourself before sending in the hard drives to a data recovery company. This is because most companies found that most of the times simple users try to recover the files all by themselves, they fail and not only. Their actions will make the recovery process even harder and if the lost information is important, someone will be in big trouble. If it's about raid data recovery better handle it quick to the professionals without touching anything.

You don't have to take chances with the recovery, it's advised to research for a data recovery company that can handle the recovery process for you. Sometimes, it can be expensive for a raid data recovery but usually the price you will have to pay for the recovery is way lower then the price you will have to pay in time and resources to have all your data recreated.

There are procedures that data recovery companies always follow when they have a recovery on the line. These procedures are followed exactly and even expand when it comes to raid data recovery. As a first step in any raid data recovery, experts have to make sure that all drives are working. For Raid 0 as an example, it is a must for all the drives to be 100% functional. When they are not functional, the drives will be taken in the clean room and will be repaired.

When all the drives will function normally, clones of all the drives will be made. During this process, your drive will be placed in a write protect mode to make sure the data will not be altered in any way. The normal recovery process will be performed on the cloned drives, again, for increased safety.

When researching for a data recovery company you will notice some of them will offer a service full guarantee, if they don't get your data back, you don't pay. A phone consultation is something that could help you also. They will also offer you absolute 100% confidentiality on your data.

Even if raid data recovery sometimes can become expensive, most companies will not charge you for an evaluation of a complex raid system. If you need the help of the experts, get it, it's the best way. After getting all your data back, make sure to always backup your information from now on.

Ask any IT manager what they think about used data networking gear and chances are their eyes will light up. Six years after the Telco bust, the secondary market for IT has grown up and with it companies have grown accustomed to buying used. But with the steep discounts come added risk and buyers are becoming savvy about negotiating the vast, complex market for pre-owned equipment.

Contrary to popular thinking, availability often trumps price as the critical factor for buying used. While manufactures like Cisco and Foundry Networks commonly stick customers with two and three-week lead times, virtually any piece of equipment can be sourced from the gray market in 24 hours. Of course the discount for used, which ranges from 50-90 percent off list pricing has proved to be the real elixir; coaxing even the most conservative buyers to board the gravy train. According to industry estimates, 70 percent of companies have experience buying second-hand gear today. What is tricky about the secondary market is finding good gear and buyers have learned a lot about how to protect themselves.

Estimates of the counterfeit and stolen goods trade for data networking equipment run as high as $40 billion, a figure deserving of some scrutiny having been published by the Alliance For Gray Market and Counterfeit Abatement (AGMA) a consortium formed in September 2001 by leading IT manufacturers including Cisco and HP. Whatever the number is, it’s big. And as online market places such as eBay have exploded so has the level of fraud.

Search for used Foundry Networks on Google or eBay and the results are myriad. Hundreds of resellers, predominately in the US, offer used switches, routers, load balancers and firewalls with varying configurations and terms of sale. With eBay’s built-in seller rating system whereby for each transaction, the buyer and seller are allowed to rate each other by leaving feedback, buyers are encouraged to select only the vendors who have a high positive feedback rating (90% and up) and a history of many such transactions.

Buyers have learned that eBay also is a haven for counterfeiters, primarily from China who list new Cisco auctions at irresistible prices. To the untrained eye, these products appear identical to the real thing and in some cases will operate like normal. The trouble comes when the end-user tries to purchase support, known as SMARTnet from Cisco only to learn that the serial number is invalid or doesn’t exist. By that time the seller has his money and has likely changed his identity online. For the customer, equipment failure is imminent and a refund is merely a pipe dream.

A quick Google search for “used Foundry switches” will garner 1,600,000 results comprising mostly news and other product information together with links to resellers who specialize in the sale of such gear. While most online users will focus on the organic links, companies with paid advertisements on the right side of a Google results page are considered credible sources as well.

Buyer Beware. Things to consider before buying used:

· Run a D&B (Dun and Bradstreet) on the company – D& B hosts a database of over 64M businesses worldwide. Through their Data Universal Numbering System (DUNS) you can access useful information on a company such as names and contact information for their principals, company credit rating, and pertinent financial information. By verifying with D&B, you can be assured that a company is in good standing and is conducting business with fair-practice in mind.
· Validate all serial numbers – Serial numbers unique identifiers that are assigned to every hardware unit. By checking a components serial number, you can verify its authenticity and ensure the unit is not stolen.
· Verify Warranty terms in writing – As with any big-ticket purchase, it is always important to clearly understand the terms of purchase. Many companies offer a limited warranty that may cover parts, but not labor. With any used product, something that functions perfectly today, may encounter problems down the road. Make sure you understand what condition the unit is in, and whose responsibility the potential repair costs are. Be aware that there are many companies that offer total repair cost warranties to end-users.
· Never pay cash – This should be common knowledge, but cash purchases are not as secure as other forms of payment. Credit cards, wire transfers, and checks all provide a record to a company and bank account. This will provide you with a paper trail to a specific person or business should there be any disputes or legal issues that come up.

Picking up the phone and calling a brick and mortar business is always the safest way of purchasing equipment but it doesn’t guarantee a buyer will not be defrauded. There are hundreds of trusted resellers in North America with a range of scale and expertise. Most firms will accept credit cards, wire transfers, and Paypal. A quick scan of a website will provide some peace of mind but buyers today understand that the more information they can glean on a vendor, the better they will sleep at night.

In the first part of this home lab tutorial, CCNA and CCNP candidates can see that there are a LOT of choices when it comes to what to buy to build your own Cisco practice lab.

Having been there myself, I know it's confusing to decide how many routers or switches to buy, and what I need at the minimum to run labs and get some great hands-on practice. Let's take a look at some lab configurations and some other lab equipment you may need.

A starter practice lab will consist of two Cisco routers and one switch, hopefully a 2950. This is a good way to get started. You will need to make sure that the routers you purchase have Ethernet ports, and at least one serial port. If possible, get routers with BRI ports, so even if you're not configuring ISDN now, you'll be able to in the future. (You will need one additional device to make ISDN work in your lab, and we'll talk about that later in this article.)

You can practice setting IP addresses and testing IP connectivity over the Ethernet interfaces, and you can configure a point-to-point connection between the two serial interfaces. (You must know how to do that before you think of taking the CCNA exams!) Depending on the switch, you can also get some practice putting the Ethernet ports in different VLANs and working with the switch IOS.

This setup does have some limitations. You can't practice trunking or Etherchannels with one switch, and you can't set up a Frame Relay cloud with this configuration. It's a good start, but you should consider getting a few more routers, including one to serve as your Frame Relay switch.

What's a Frame Relay switch? Good question.

The Frame Relay Switch

As you know from your studies, Cisco routers are DTEs by default. The Frame Relay cloud is made up of DCEs.

In a lab environment, you need a device to serve as the Frame Relay cloud. This device will have DCE interfaces, and will actually be performing frame relay switching. But this isn't a switch in our lab - it's a Cisco router.

There are plenty of Cisco routers that make great frame relay switches. Get one of those and a couple of DCE/DTE cables, and you can configure the router as a frame relay switch and have your own working frame relay cloud in your lab!

The Cisco router you choose as your frame relay switch should have at least four serial ports, and if you can get more, great. It's always good to have spare ports.

If you get four Cisco routers, with one as your frame relay switch, you can set up a frame relay cloud and practice your hub-and-spoke frame configurations. Even better, as my labs do in my CCNA Study Guide, you can set up a frame relay cloud and a point-to-point Serial connection. This will help you get real hands-on practice with such features as EIGRP variance.

With that four-router configuration and one switch, you can get some great hands-on experience with many CCNA features that many candidates just read about. If you can add a second 2950 switch, you can practice different spanning-tree configurations, such as changing the root bridge of a given VLAN, working with VLAN Trunking Protocol (VTP), and configuring your own Etherchannel! (You will need some crossover cables to connect your two switches.)

Let's take a look at one more important piece of lab equipment: the ISDN simulator. You can't just take a straight-through cable and connect your BRI interfaces directly. You need a device called an ISDN simulator to act as the phone company in your home network. The newer simulators let you set your own phone numbers and SPIDs; most older ones have a preset phone number and SPID that you must use. Either way, you get truly valuable experience getting hands-on work with ISDN, especially watching PAP and CHAP debugs and understanding the authentication process.

ISDN simulators can set you back a few bucks. I recommend you visit www.ebay.com and search for ISDN simulator. There are generally 20 - 30 used ones on there at any given time. Be careful to purchase one with at least a 30-day guarantee. They are robust devices for the most part, as there is one in my home lab that I've had for three years (when they were really expensive!), and it's never given me a bit of trouble.

There are many online vendors that will sell you a new one, but obviously the price is going to be higher. One company I've had good experiences with is www.vconsole.com. Make sure to shop around, as there are plenty of ISDN simulator manufacturers out there on the web. Vconsole is the only one I've purchased a new unit from, and the 10-port simulator I use in my classes has worked beautifully.

There is another piece of lab equipment that isn't necessary for your lab, but you'll find life is a lot easier with it. And just as the frame relay switch is really a router, so is this device: the access server.

Access servers are devices with an asynchronous port that an octal cable can connect to. What you do is connect your blue console cable (officially referred to as a -rollover cable-�) to the console port of your access server. You then take an octal cable, and connect one end of the cable to your Async port. The other end of the cable, as you'd expect from the name, consists of eight smaller RJ-45 connectors. Each one of those goes into the console port of one of your other lab devices, and you configure the access server to allow one-key access to each of the other devices in your practice lab.

The configuration of the access server is a simple one, and I'll have an example of configuring your access server and frame relay switch up later today.

Not everyone can start with a lab this size, so be careful when you buy your first routers. Make sure that they're not just giving you good practice now, but that they allow for future growth of your lab. As you add a frame relay switch, an ISDN simulator, and an access server, you'll get the hands-on experience you need to be successful on the job, acquire the self-confidence and troubleshooting skills needed in the testing room and on the job, and to solve any simulator question on your CCNA and CCNP exams with ease.

Have fun!

Cisco certification candidates, particularly CCNA candidates, must master binary math. This includes basic conversions, such as binary-to-decimal and decimal-to-binary, as well as more advanced scenarios involving subnetting and VLSM.

There’s another conversion that might rear its ugly head on your Cisco exam, though, and that involves hexadecimal numbering.

Newcomers to hexadecimal numbering are often confused as to how a letter of the alphabet can possibly represent a number. Worse, they may be intimidated – after all, there must be some incredibly complicated formula involved with representing the decimal 11 with the letter “b”, right?

Wrong.

The numbering system we use every day, decimal, concerns itself with units of ten. Although we rarely stop to think of it this way, if you read a decimal number from right to left, the number indicates how many units of one, ten, and one hundred we have. That is, the number “15” is five units of one and one unit of ten. The number “289” is nine units of one, eight units of ten, and two units of one hundred. Simple enough!

Hex numbers are read much the same way, except the units here are units of 16. The number “15” in hex is read as having five units of one and one unit of sixteen. The number “289” in hex is nine units of one, eight units of sixteen, and two units of 256 (16 x 16).

Since hex uses units of sixteen, how can we possibly represent a value of 10, 11, 12, 13, 14, or 15? We do so with letters. The decimal “10” is represented in hex with the letter “a”; the decimal 11 with “b”; the decimal “12” with “c”, “13” with “d”, “14” with “e”, and finally, “15” with “f”. (CCNA candidates will remember that a MAC address of “ffff.ffff.ffff” is a Layer 2 broadcast.)

Practice Your Conversions For Exam Success

Now that you know where the letters fall into place in the hexadecimal numbering world, you’ll have little trouble converting hex to decimal and decimal to hex – if you practice.

How would you convert the decimal 27 to hex? You can see that there is one unit of 16 in this decimal; that leaves 11 units of one. This is represented in hex with “1b” – one unit of sixteen, 11 units of one.

Converting the decimal 322 to hex is no problem. There is one unit of 256; that leaves 66. There are four units of 16 in 66; that leaves 2, or two units of one. The hex equivalent of the decimal 322 is the hex figure 142 – one unit of 256, four units of 32, and 2 units of 2.

Hex-to-decimal conversions are even simpler. Given the hex number 144, what is the decimal equivalent? We have one unit of 256, four units of 16, and four units of 4. This gives us the decimal figure 324.

What about the hex figure c2? We now know that the letter “c” represents the decimal number “12”. This means we have 12 units of 16, and two units of 2. This gives us the decimal figure 194.

Tips For Exam Day

Practice your binary and hexadecimal conversions over and over again before you take your CCNA exams. Binary math questions come in many different forms; make sure you have practiced all of them before exam day. The number one reason CCNA candidates fail their exam is that they’re not prepared for the different types of binary math questions they’re going to be asked, and that they aren’t ready for hexadecimal questions at all.

You don’t have time to learn how to do in on exam day. You’ve got to be ready before you go into the exam room, and the only way to be ready is a lot of practice.

Finally, make sure you read the question carefully. You’ve got hex, decimal, and binary numbers to concern yourself with on your CCNA exams. Make sure you give Cisco the answer in the format they’re looking for.