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#756: Working Around a Failed Optical Drive, Masking and Cascading Failures, Spaces and Jiggly Icons


Happy Tuesday,

Well, last week’s updates to the MacBook Pro line were certainly significant. Huge speed increases are always welcome, particularly when there’s little to no effect on battery life. The big news to me is the completely new I/O port, formerly code named Light Peak, called Thunderbolt in its final implementation. At 10GB/sec it completely blows away USB 3.0 and FireWire 800 in every regard. Of course, with any new technology like this, the main stumbling point at first will be availability of peripherals to take advantage of the interface. Rest assured, Small Dog will carry a great mix of Thunderbolt-compatible devices as they are released.

Apple has done this before with USB on the original iMac and FireWire on early PowerBook G4s. With Apple’s always-growing market share and enviable brand respect, I’m sure we’ll see swift adoption of this new technology in the weeks and months ahead.

The new stuff will keep coming this week, as Apple announced a press event on the second. While unconfirmed, the graphic Apple used in their announcement makes it pretty clear the event will be focused on iPad. We’ll have analysis and commentary on our blog, Barkings when the time comes.

As always, thanks for reading, and keep in touch.


  Working Around a Failed Optical Drive  

Many people don’t realize their optical drive has failed until they need to install a new piece of software or are having their computer evaluated for trade-in. After all, more and more software titles are moving towards download-only, and the App Store is evidence that this trend is only gaining momentum. As with fans and hard drives, optical drives are one of the few mechanical devices within your computer that can fail logically or physically. A logical failure would be when the drive itself is not recognized by the computer, and a physical failure would be where the drive doesn’t accept disks, scratches disks, etc.

If you must install software immediately and your optical drive is broken, you could always use Remote Disk using your network and another Mac. To begin, insert the disk into the Mac with the working optical drive. Then open System Preferences and select the Sharing preference pane. In there you will want to click on the DVD or CD Sharing box that appears first in the list. There is a secondary check box there that you can check to require your authorization before a remote Mac accesses your optical drive.

With sharing turned on, turn your attention to the Mac requiring the software installation. Fire up Terminal and paste in the following commands exactly as they appear,pressing return between each command:

defaults write EnableODiskBrowsing -bool true

defaults write ODSSupported -bool true

After entering the commands in Terminal, you can either restart the machine, log out and back in, or type “killall Finder” in Terminal. The next time you open a Finder window, Remote Disk will appear under the devices in the side bar. Click on Remote Disk, and it will post a request to the machine sharing the drive asking whether or not the connection and usage is to be allowed. Install your new Applications or import your new music. To remove the disk sharing option on the unit with the failed drive, simply enter the terminal commands once again and substitute false for true, and it will disable the practice once again. Don’t forget, you’ll need to log out and back in, restart your computer, or reboot the Finder by typing “killall Finder” in Terminal before any changes will become effective.

  Repair of the Week: Masking and Cascading Failures  

One of the challenges of troubleshooting is that the same symptoms can have multiple causes. Another is that failing components can cover up or mimic symptoms of other failing components. This is often called masking. We had a MacBook Pro come into the shop that, when powered on, got to the grey screen; the apple never appeared on the screen, and the machine never fully booted. With a symptom like this, the first thing that comes to mind is the hard drive, and the initial diagnosis seemed to bear this out.

The machine passed Apple’s service diagnostics except for the hard drive tests. In fact, the hard drive tests weren’t even available, meaning that the diagnostic tool didn’t even recognize that there was a drive to test. Pulling the drive and testing it outside the machine confirmed that the drive had an abundance of bad sectors, a sure sign that it needed replacing.

Running the Apple diagnostics also showed that the machine would boot from a known good volume—the test suite boots the machine with a version of OS X via one of the USB ports. With this information in hand, the technician ordered a replacement drive. But when the drive arrived the next day and was installed, the machine still refused to boot. The original symptom persisted: it booted to a blank grey screen. It was obvious at this point the problem went beyond the hard drive.

After replacing the interconnect cable between the drive and the logic board and getting no change in the machine, a logic board was ordered. After installation the machine booted normally and was returned to the customer. This repair perfectly illustrates the concept of masking. In this case, even though the symptoms were classic for a failing hard drive, the real reason the machine would not boot was a logic board failure. The situation was further confused by the fact that the drive need replacing as well.

As an aside, at pickup time the customer asked a question we get a lot in these kind of cases: Why does my new machine have two bad parts? Understandably, this can cause people some concern. After all, one of the reasons people choose Apple is the high reliability of the hardware. The answer is that the machine is an interconnected system, not a collection of separate parts. When a part fails, it can cause serious damage to other parts in the machine. In the logic board/hard drive interconnect there is also a power circuit in addition to the data circuits, so there is even more chance for a failure such as a short circuit to cause problems. In this case we would never be able to say which went first, but in my experience the failure of one of these components almost certainly caused the failure of the other, necessitating the replacement of both. We call failures of one component due to another “cascading failure.”

  Reader Write In: Spaces and Jiggly Icons  

Di asks, “I’d love a rambling about Spaces. Is it possible to have multiple desktops for one app?”

Well, Di, Spaces is an aspect of the Mac OS that enables you to have multiple desktops for organizational purposes. We had a technician here who was a multi-monitor addict and had a hard time adjusting to having only one monitor on his bench here in South Burlington. In order to compensate for this, he would use Spaces to create several desktops to organize his applications and work flow as though he had several monitors. To my knowledge, you can’t use Spaces to create multiple desktops for a single application. What you can do is have that application appear in each Space, but as far as I know, it doesn’t virtualize multiple instances of that application being open. You still only have one install of Word, for example. A good quick intro to Spaces is the Apple Knowledge Base article HT1624 that you can access here:

Kirsten asks, “What does it mean when the icons on the iPhone 4 start jiggling? Also, I have noticed that I can switch apps but can’t open more than one page in Safari at a time.”

To answer your first question, Kirsten, the jiggling icons signify that you’ve held your finger down on an app for a few seconds longer than it would take to start that app. This enables you either to rearrange the icons by dragging them or to delete apps from your iDevice by tapping on the ‘x’ in the upper-left corner of each icon you wish to remove To stop them from jiggling, just click your home button once. This applies not only to your iPhone 4 but also to any of Apple’s iDevices running the current version of iOS.

As far as Safari is concerned, you can open another Safari window by tapping the icon that looks like two squares on top of one another, located in the lower-right corner of the screen. The screen will change slightly, and you’ll see a button for ‘New Page’ in the lower-left corner. Just tap that, and you’ll now have multiple browser windows. That double-square icon will now have a number in it showing how many windows you have active in Safari.

If you have any questions for the service team here at Small Dog Electronics, send an email to or find our direct contact info on the Small Dog Contact Page

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