TV with DVR & Internet: $84.90/moCan't get on the Internet? Can't print to network printer? It's bound to happen sooner or later. Wired Ethernet networks are pretty reliable, wireless ones can be brutally finicky. But no matter what type you're using, it's good to be prepared for networking failures in the future.
When there is a networking problem, the knee jerk reaction may be that there is something wrong with the computer. Perfectly understandable.
But the first step in debugging a networking problem should not involve any of the computers. Rather, you should look at the lights on the box(es) sitting at the hub of the network. The hardware is talking to you and may have something useful to say.
The box(es) may be a number of things. Often there is a broadband modem (cable or DSL) and a separate router. There may even be a third box for VOIP to which a normal telephone is connected. On the other hand, all these functions may be combined in a single box. The advice is the same either way.
Before trouble strikes look at the box(es) holding your network together and make a note of the normal state of every light while the network is functioning properly. Is the light on or off? Green or Amber? Solid or blinking?
So that it's always at hand, I suggest keeping this cheat sheet right next to the device in question. Maybe even tape it to the box, so it can't get lost. Now, when the network fails, the first thing to check is the lights on the box(es).
That's step one. Step two is to examine each box and make a note of the vendor and model number. Then go online to learn what every light can tell you. It's one thing to know that a certain light is normally green, but exactly what does it mean when the light is amber? Or blinking green instead of solid green?
I try to find the manual for the device at the web site of the hardware manufacturer. In addition, I try to find documentation on the lights at the website of the broadband provider. Cable and DSL modems can be modified by an ISP, so their documentation may be more accurate than that from the hardware manufacturer.
If you were given a manual/booklet/pamphlet with the device and can still find it, great. But this would be my last choice for information as it may not be up to date, may cover multiple models or may not reflect customizations made by the ISP.
If, at your ISP's web site, you can't find anything documenting the meaning of each light, then contact your ISP and ask them. Someday, you may be very thankful you did.
Today, July 10th, the web site of The Wall Street Journal is free, sponsored by Dell. Normally the vast majority of the site is available only to paying customers - of either the web site or the hard copy paper.
I mention this to draw attention to an editorial that appeared in the paper on July 3, 2007 entitled Google v. Microsoft.
Background
Windows Vista includes desktop search functionality out of the box and Google offers a free desktop search application that anyone can download from their web site and install. Google complained to Microsoft's antitrust regulators at the Justice Department that there isn't a level playing field when it comes to competition for Vista desktop search applications.
Mistakes
The editorial says
"Web-based applications like desktop search are increasingly central to Google's business prospects...".
The "web-based" description is off base. Desktop search is a desktop application and is not based on the Web. Google's own desktop search application can be installed and run just fine on a computer with no connection to the Internet.
At first I thought this might be just a typo. But the mistakes continued. Quoting again:
"In the original Clinton Administration case against Microsoft, the company was deemed a monopoly because it made 100% of operating systems called Windows..."
Yikes. By that logic, Apple is a monopoly because it makes 100% of the operating systems called OS X. And IBM was a monopoly way back when it made each copy of OS/2. And strike three:
"It is easy for a business with a superior service to peel away the customers of everyone else. That's what accounts for the success of Google's basic Internet search in the first place."
Google never pulled away a single "customer" back in its early days. It converted users of other search engines, such as Alta Vista and Hotbot. I see two differences between "customers" and "users".
For one, users of other search engines never paid for the service. Also, they had very little invested in Alta Vista and the other search engines. That is, there was pretty much no learning curve involved when switching from one search engine to another.
This is very different from say, the competition between Windows and the Mac OS X operating system. Switching involves paying a non-trivial amount of money to get a copy of OS X and a large learning curve to get proficient using both the new operating system and new application programs required to do the same work that was previously done under Windows.
Whatever the advantages of OS X may be, the cost of switching is huge, both in financial terms and time. Switching operating systems could not be more different from switching search engines. To quote myself:
"You don't read PC magazine for mutual fund advice and you shouldn't read the Wall Street Journal for computer advice."
When I said this in the past I was often referring to Walter Mossberg who, in my opinion, has on multiple occasions offered bad computer advice. But this editorial was written by someone who doesn't understand computers at all. It is more off base than Mr. Mossberg ever was.
To a computer nerd like myself, RAID refers not to a bug spray but to various ways of hooking together multiple hard disks. The various approaches are referred to as levels. Raid levels one through five are designed to decrease the chances that a hard disk failure will result in lost data. Typically RAID configurations are used in server machines as opposed to personal computers.
Raid level zero, however, is the black sheep of the RAID family. It's goal is performance rather than reliability. I'm writing this posting because two of my clients have been burned by their inadvertent use of RAID level zero. Consider this a word to the wise.
Client one purchased an external hard disk from LaCie. This person needed lots of storage space and, at the time, this particular model was top of the line, offering the most storage capacity. The reason it offered more storage than cheaper competing models is that internally there were two 3.5-inch hard disks instead of the usual one. While it looked to the outside world like one chunk of 500 gigabytes, the internal reality was that there were two 250 GB hard disks.
Client two owned a high end Dell XPS tower with two internal hard disks. This person wanted the latest and greatest and fastest computer. Thus, Dell configured the two internal hard disks for speed--RAID level zero. Like the old saying goes, be careful what you wish for, you may get it.
The hard disk is significantly slower than the processor and RAM. Thus to get the fastest read/write performance, RAID level zero stores half of a file on one hard disk and half on the other. Using both hard disks in parallel should reduce the total time needed to write a file.
To someone designing a computer system, the term single point of failure is like kryptonite to Superman. The term refers to a single point in the system which should it fail, would bring down the whole house of cards (so to speak). In an automobile, each tire is a single point of failure, thus they all have a spare in the trunk.
In a personal computer the hard disk is a single point of failure. However, in a RAID level zero configuration, there are three separate single points of failure involving the hard disks. Should either hard disk fail, all is lost because each disk contains half of every file. Oops.
In addition, both of my clients were also dependent on the RAID hard disk controller, the thing with the intelligence to split files as they are written out to the hard disks and re-assemble them back together when read. If the hard disk controller fails, the files may still be alive and well and happy on the hard disks, but you can't read them. Recovering from a RAID level zero controller error might cost thousands of dollars, as its a job for the most sophisticated data recovery companies.
RAID Zero with a failed disk. Click for full-size.
In the case of the client with the Dell computer, it was fairly easy to determine that the problem was with one of the hard disks. Replacing it, re-establishing the Raid zero environment and then restoring a disk image backup got the machine up and running. Disk image backups will be the subject of an upcoming posting on this blog.
The client with the external hard disk lost everything. Not that it mattered, but I couldn't even determine if the problem was with one of the hard disks or the RAID controller.
Update: July 8, 2007. Originally I had said the hard drive was the slowest thing inside the computer, except for the fan. Someone pointed out that optical drives are even slower, so that sentence now says the hard disk is slower than the processor and ram, which was the point I was trying to make.
Note: See
the comments on the original posting.
Update: July 13, 2007. See Following up on RAID Level Zero
If Carl Sagan were alive he might point out that there are billions and billions of blogs. So why read this one?
This blog is for people for whom the health and well being of their computer and/or data is important.
Computer problems are inevitable, and to someone who depends on a computer problems can be disastrous. That's why I'm here.
Defensive computing is about taking steps when things are running well, to avoid or minimize problems down the road. In short, it's about being smart and planning ahead. This blog will not be computing for dummies. That said, no technical background will be needed to understand any of the postings to come. Just experience using computers.
I use the term "computers" because this blog will not be limited to personal computers. While much of it will be about PCs running Windows, I will also write about other operating systems and computers that are in no way "personal", meaning servers and beyond.
How important are the computers you deal with? Suppose they were stolen. If the loss is a nuisance and your biggest gripe is the replacement cost and hassle, this blog is not for you. It's for people for whom a computer failure would be a huge problem, as in not being able to run a business or perform your job.
Many people who depend on their computers are on their own, without an IT department or computer nerd nearby. If you work at a very small business, are self-employed or part of the growing home based workforce, then you've come to the right place. This blog's for you.
My goal is that you'll learn enough about computers to keep yours happy and healthy and doing the job for which it was purchased. I will try to make the blog educational, fun and an easy read. Postings will probably be a bit longer than is usual for a blog and they may not be as frequent. Hopefully, you'll find them useful.
Defensive Computing also entails making decisions based on accurate information. All too often, computer related articles in the media contain technical mistakes or omissions. I'll be correcting some of these articles. Newspapers, watch out.
There will be no bias in this blog. I'm not an enthusiast or opponent of any particular operating system or application. For example, I use Firefox all the time and tell everyone that will listen to do the same. Still, it has its share of faults and I've documented many on the Firefox page at my computergripes.com web site. Nothing is ever black or white.
Finally, this blog is not about gadgets.
This will be an iPhone, iPod and iTunes free zone. No electrons will grace this space devoted to cellphones of any type. Digital cameras? Nope. PlayStation, Xbox? No way. High Def TVs? Fuggedaboutit.
Think NBC - Nothing but computers.
Still, this leaves a lot of ground to cover.
Michael Horowitz has no business relations, investments or affiliations with subjects he covers.
