Thoughtful, detailed coverage of the Mac, iPhone, and iPad, plus the best-selling Take Control ebooks.



Pick an apple! 
Syslogd Overwhelming Your Computer?

If your Leopard (Mac OS X 10.5) system is unexpectedly sluggish, logging might be the culprit. Run Activity Monitor (Applications/Utilities/ folder), and click the CPU column twice to get it to show most to least activity. If syslogd is at the top of the list, there's a fix. Syslogd tracks informational messages produced by software and writes them to the asl.db, a file in your Unix /var/log/ directory. It's a known problem that syslogd can run amok. There's a fix: deleting the asl.db file.

Launch Terminal (from the same Utilities folder), and enter these commands exactly as written, entering your administrative password when prompted:

sudo launchctl stop

sudo rm /var/log/asl.db

sudo launchctl start

Your system should settle down to normal. For more information, follow the link.

Visit Discussion of syslogd problem at Smarticus



Related Articles



Introducing Our New FlippedBITS Column

Send Article to a Friend

Today I’d like to introduce a new series of articles we’re calling FlippedBITS. Our premise is that technology breeds misconceptions, and far too often, due to a lack of information, we develop mental models of the way things work that are plausible — but wrong. Those mistaken ideas, in turn, make it more difficult to solve everyday problems and can lead us to waste time, effort, and money. In each installment of FlippedBITS, I’ll examine one or more of these misconceptions and do my best to set the record straight.

My 2-year-old son is still learning the basics of how the world works, and it’s fascinating to watch his understanding of technology evolve. Just a few months ago, he’d pick up a remote control and try to talk on it like a telephone. In his mind, any oblong plastic box with buttons on one side must be a telephone — it’s easy to see how he might make that mistake. (And, in all fairness, we had a telephone and a remote control that looked mighty similar to each other.) Now he understands that a remote control is different — it’s the thing we point at the TV to make it play his favorite shows. But then he became confused and frustrated when we handed him a toy remote control that only made noise when he pressed the buttons; he couldn’t understand why the TV wouldn’t respond.

We expect kids to make these kinds of errors, and we laugh knowingly as we watch how they try to put something into one logical category, notice that it doesn’t quite fit, and then try another. This is all part of growing up. But in fact, we never stop trying to make sense of the world. We encounter a new thing we don’t entirely understand, and we automatically — perhaps unconsciously — start trying to construct a mental model of what must be happening behind the scenes. These models not only help us explain what we’re seeing, they help us predict how things will work in the future. It’s just that sometimes, through no fault of our own, we guess wrong.

For example, I remember the first time I heard of this newfangled device called a “laser printer.” I was a freshman in college. I got that paper went in blank and that, due to something involving a laser, it came out with crisp black text. But the initial idea I had about how this worked was that the laser was somehow burning the letters directly on the paper, because after all, burning is what lasers do. Later, when I found out that laser printers used a black powder called toner, I had to revise my theory. Maybe the paper was covered with toner before the laser zapped it, and the heat from the laser caused the toner to melt in spots and stick to the paper. That turned out to be wildly wrong too, of course. I had no idea at the time that a laser beam could reverse an electrostatic charge that otherwise causes toner to stick to a drum, that when paper rolled along that drum, it picked up the remaining toner (again, due to electrostatic attraction), and that a combination of heat and pressure then fused the toner to the paper. My theories had seemed reasonable based on the available information; they even correctly predicted that the paper would come out of the printer warm. But my mental model didn’t happen to reflect reality.

Misconstruing how a laser printer worked had no negative consequences for me. But sometimes erroneous mental models lead to serious problems. If your mental model of how a car’s air bags work is that they offer complete protection in any sort of crash, that could lead you not to bother wearing a seatbelt, which might prove deadly if, for example, your car flipped over.

I get lots of technical questions from people who have read my books and articles or heard me speak somewhere. A fair percentage of the time, the questions are phrased in a way that shows they come from a mistaken mental model. For example, in the last several weeks at least three different people have asked approximately the same question: “Since FileVault encrypts all the files on my disk, doesn’t that mean when I copy a file to another disk, it’s still encrypted?” No! It absolutely does not mean that. (I’ll explain why in a future FlippedBITS article.) But I can easily see how someone might draw such a conclusion — and misunderstanding something like that could cause someone to make an unsafe decision about how to handle sensitive files.

I’ll admit it: When I hear questions like this, I sometimes have to fight the temptation to roll my eyes and say, “What an idiotic idea!” But I’ve had (and probably still have) plenty of idiotic misconceptions myself. Not understanding something, or having a faulty conception of how it works, doesn’t make you stupid. It only means you haven’t yet acquired enough information about something. I’ll do my best to supply those missing facts and put us all on the right path. I already have a healthy list of prospective FlippedBITS topics, but if there’s a topic you think might be an appropriate fit, please feel free to suggest it.

So, whence the name “FlippedBITS”? Apart from the fact that we at TidBITS like to append “BITS” to everything, we thought that flipped bits would be an apt description of the kind of error we’re trying to correct. Computers, as you know, store information as a series of ones and zeroes. Every “slot” that can hold either a one or a zero is a bit. If the bit’s value is zero and you flip it, it becomes a one. Flip it again, it’s back to zero. Sometimes bits get flipped inadvertently due to programming errors, mechanical failures, media degradation, cosmic rays — really! — or other random occurrences. And unfortunately, a single flipped bit — a one where a zero should be, or vice-versa — can mean the difference between a program succeeding and failing. After all, 01110111 is “w” in binary, but 01110011 — almost the same, but with one bit flipped — is “s.” Sometimes a change as small as a single flipped bit can spell the difference between a “win” and a “sin”!

With that, allow me to direct you to the first article in what I hope will be a long and helpful series: “FlippedBITS: Booting Your Mac from a Duplicate” (13 March 2013)


Make friends and influence people by sponsoring TidBITS!
Put your company and products in front of tens of thousands of
savvy, committed Apple users who actually buy stuff.
More information: <>

Comments about Introducing Our New FlippedBITS Column

rastarman  2013-03-13 15:54
I didn't state my previous comment properly. What I meant to say is that when opening an app on a clone, be sure that you are indeed opening the app on the clone, and not your normal internal drive. It's possible when using shortcuts, especially Spotlight, to open the internal drive app and not the one on the clone.
Joe Kissell  An apple icon for a TidBITS Staffer 2013-03-13 16:01
Yes, that's true, if your normal startup volume is still connected, you could potentially open the "wrong" app or folder by mistake. It's not a huge problem with apps, but it can be with files/folders if you save to the wrong place.
Lance Diernback  2013-03-13 17:58
Joe: As a software engineer of 40+ years experience, the last 28 in the space program, I immediately hit on a possible misconception flowing from your article. You said: "Sometimes bits get flipped inadvertently due to...cosmic rays..." How many people immediately interpreted "cosmic rays" as that flippant (!) way we refer to unknown causes when, in fact, you were literally correct?
Glenn Fleishman  An apple icon for a TidBITS Staffer 2013-03-13 18:08
And, coincidentally enough, the MSL Curiosity is having trouble right now. Its "A" computer had memory glitches and the "B" backup is running diagnostics. It's thought that "A" was hit by cosmic rays which may have permanently damaged memory locations.
Joe Kissell  An apple icon for a TidBITS Staffer 2013-03-13 18:34
Yeah, cosmic rays can do some real damage to computers. I have never thought of "cosmic rays" as meaning anything other than their literal meaning, but then, I'm a science kind of guy.
Adam Engst  An apple icon for a TidBITS Staffer 2013-03-14 06:31
I actually added those words in editing, since I've always been tremendously amused that cosmic rays really can flip bits. What I like about it is that it's both flippant and true - my hope is that people will think "That's funny!" and at some people realize that it's also real.
A few rules of thumb for disk clones (I'm sure there's more, have been doing this so long it's become rote)--

Don't use any aliases that appear on your Clone. They point to something on the original disk; easiest by far is to ignore them.

Review and trim login items.

Set a different desktop picture.

Run Disk Utility and Disk Warrior before creating a clones and, to be safe, before Restarting with one.

And of course, use the fact your machine is booted from the Clone to run utilities and repairs that can't really be done from the same machine.
Joe Kissell  An apple icon for a TidBITS Staffer 2013-03-16 18:21
Actually, not so about aliases—they're relative, as long as they're created from items on the disk you've started up from. (But that's another article…)