Applejack: Getting New Features

Applejack, the command line troubleshooting utility for Mac OS X, is undergoing prerelease testing now for version 1.4.3rc3, which adds a new experimental expert mode. From the read me:

+ Experimental expert mode exists, but is currently hidden until it can be tested further. (see Appendix B). The only well-tested options at this point are the memory test using the included Memtest utility, and the option to disable auto login.

This is great, because among other neat features, it adds the memtest utility as well, which will save you the $1 download charge from its developer.

Memtest and Applejack are must-have utilities, IMHO. Memtest saved my butt on bad memory (via the GUI version in the form of rembr), whereas Tech Tool Pro told me my memory was fine. Wrong! Changed it out and my numerous problems went bye-bye!

Memory = the source of many problems!

For the last several months, I had numerous problems with my old G4 AGP dual 1.2, which has been as upgraded just about as far as it can go. The problems included recurrent program crashes (especially Safari) and random kernel panics.

I used a little utility called Rember and discovered that a few memory sticks I had were bad. Tech Tool Pro (grumble, grumble) did not catch these errors, so if you think you're having memory issues, please run another utility (apparently, the hardware test disc Apple ships with newer Macs can catch these problems too). You can also run Memtest (which is really the command-line basis of Rember); the author charges $1 to download it (very reasonable given that you can boot in single-user to test MOST of your RAM).

In my case, Memtest wasn't necessary. Rember caught the defective RAM right away, and I narrowed it down to 2 sticks by pulling them one at a time, restarting, and testing with Rember until the errors were gone.

I had 2 bad DIMMs--one at 128 MB and another at 512 MB. So I ordered 2 new 512 MB sticks from OWC (with lifetime warranty). The new memory checked out fine with Rember, and I've had no kernel panics or other major issues since installing it. The old Mac is rock-solid!

Now, how did this happen? I think a Tiger update somewhere down the line didn't agree with those two older RAM sticks. The lesson is to suspect bad RAM (or other hardware) if you're having weird crashes and random panics suddenly.

ATPM 11.08 - How To: Is Your Memory Failing?

ATPM 11.08 - How To: Is Your Memory Failing?:

Great information on testing your Mac's memory in single-user mode. Memory failure is a common kernel panic problem.

Here's another great link on the same subject at Macworld:

http://www.macworld.com/2006/02/features/speedmemory/index.php

DamagedFiles, Recovered files, and lost+found: huh?

It's really important to treat a DamagedFiles folder that shows up after a crash and disk repair with respect. Research what each file or folder is by using the symlink to go to its original. Replace those files from a backup and repair permissions! There has been data loss.

Macworld: News: Inside Mac OS X 10.4.2:

"Next, the new Disk Management repair code creates a folder named DamagedFiles at the root level of the disk in question, and creates a real Unix symbolic link (not a Mac OS alias of any kind) for each of the affected files, named with the original CNID and the file name. In our example, if your Safari Bookmarks file had the file ID 45892 and the picture that overlapped an extent with it had file ID 81834, the DamagedFiles folder would contain two symbolic links, one named "45892 Bookmarks.plist" and one named something like "81834 DSCN0001.JPG", depending on the image's original filename. As noted, only one of these files can even possibly contain correct data, and they may both be corrupted. Thanks to the symbolic links, you can easily find them, and determine which newly untangled files to keep and which to replace.

Utilities like DiskWarrior have long repaired overlapping extents with similar procedures, but it's great to have this built into the operating system, if for no other reason than that Mac OS X uses this code to verify and repair your file system during startup when the computer wasn't properly shut down. If you see a DamagedFiles directory show up on the root level of your hard drive, stop what you're doing and look at the files within it. See which of the files are damaged, and either replace them from backup or recreate them. Then run DiskWarrior if you have it, or boot into single-user mode and run fsck so it can verify there are no more problems with your disk. (You can boot from your Tiger installation disk and run Disk Utility, but since it doesn't contain the Mac OS X 10.4.2 version of this code, it won't do as well with overlapping extents, so we recommend single-user mode first.)"

More info can be found here as well.

Also keep in mind you might see orphaned files stuck in a folder at the root called "lost+found":

MacDevCenter.com -- Top Ten Mac OS X Tips for Unix Geeks: "lost+foundThis directory stores orphaned files discovered by fsck."

If you find a Recovered Files folder in your trash when starting up, Apple has the explanation here. Basically, OS X is cleaning up after applications that either crashed or did bad housekeeping:

Mac OS X 10.4 Help: A folder called Recovered Files appears in my Trash: "One or more Recovered Files folder may appear in your Trash after restarting your computer."

PMU problems? Hope not.

I've started seeing this message:

Jul 27 17:45:09 localhost kernel[0]: ApplePMU::PMU forced 

shutdown, cause = -122

I'd like to think it's a faux pas, but I think I'm reaching the physical and technical limits of what my old G4 can do. Tiger will be the last OS installment on this machine until I can replace it.

I've added a new video card (that powers 2 monitors), several hard drives, an firewire audio interface, a USB 2.0 card, and a processor upgrade. So I'm not surprised to see all these problems cropping up.

I'm also having a lot more kernel panics, freezes, and various application crashes. Not sure what to do next.