Unstable Mac! Advice for testing RAM?
April 4, 2007 11:15 PM   Subscribe

My Mac is totally messed up! Help! (Hardware issue, probably ram chips, maybe HD)

Powermac G4 tower running 10.4.9. 2x 232GB Harddrives("A" and "B", 1 160GB HD "C". 2 GB Ram (4x 512MB).

Last week:
Drives A and B are in a mirrored RAID array created by Softraid 3.3 (Have been for about a year now). My computer starts getting crazy unstable. Crashing, kernel panics abound. Try Diskwarrior on Drives A+B. Crashes during Diskwarrior treatment. Try Disk Utility. Computer keeps getting more unstable until it won't start up off of Drives A+B. OK, fine. Starting up off of Drive C

Running off of Drive C. Much more stable. Decide I'm going to reinstall Tiger on A+B. No luck. Tiger won't install because Drives A+B can't pass their Disk Utility Check. Run Diskwarrior. Works this time. Try to install tiger. No luck. Installs most of the way to the end, and then says "There were errors during the installation...Please try again." OK fine. I get rid of Softraid, split the mirror in half, and initialize one of the drives with Apple Disk Utility, zeroing out all the free space to catch bad blocks. Try installing Tiger again. Same problem.

According to http://docs.info.apple.com/article.html?artnum=106693, this is likely a RAM problem. I tried fiddling with the RAM in the beginning, swapping out chips and not noticing much more stability, but I wasn't systematic enough about it to categorically say that I tested every chip. Techtool checks of my RAM all came up fine. Unfortunately, my computer is too stable right now to test this theory without trying to install OSX 4 times with just 1 stick of ram in it each time (as the only reproduceable symptom is the failed OSX install). Can I figure out which is the broken stick some other way?

Is this even likely to be broken RAM, since my computer is basically working off of Drive C? (There have been scattered stability problems [none of which come to mind at the moment, unfortunately], but nothing like last week)
posted by anonymoose to Computers & Internet (13 answers total)
If you think it's really the 4 ram sticks are causing the problem, you could reduce testing down to a max of 3x. Seems like you could test 2 sticks at a time. If the 1st pair of sticks are bad, you then test them individually. If the 1st pair are ok, then you test the 3rd and 4th stick individually.

I've got no experience with RAID arrays so I can't help you there. But my random, irrational gut feeling is that it's somehow the raid that's somehow causing the problem. Only because HD's seem to die on me more than ram sticks.
posted by Cog at 11:24 PM on April 4, 2007

hm.. no. i disagree with the RAM conclusion. that appledoc is not tremendously focused on your kind of problem. and "scattered" stability problems also point to hard drive failure or the motherboard.
posted by phaedon at 11:29 PM on April 4, 2007

also, s "not that versed with raid arrays" disclaimer.
posted by phaedon at 11:30 PM on April 4, 2007

Sounds like you need to rule out the bad RAM. Best way to do that is by running Apple Hardware Test.

Depending on the vintage of your Mac, either AHT is on the install disc for the OS, or on a separate disc in the same foldery thing.

Here are two articles that walk you through the process:
General Instructions
Specific Instructions for Intel-Based Macs, from Apple

If the machine isn't even stable enough to run AHT, then you'll have to start physically swapping RAM chips with known-good ones in order to isolate the one or ones that are bad.
posted by Kadin2048 at 11:31 PM on April 4, 2007

Doesn't sound remotely like RAM to me since the stability improved when you booted off a different drive.

It sounds like you have a failing drive to me.

You can reformat to get rid of bad sectors all you like, but if the hardware is failing you'll still have problems.
posted by unSane at 5:47 AM on April 5, 2007

Ditto to unSane. Classic symptoms of one drive in a RAID array failing. Have you tried booting from each of the RAID drives separately, since they're mirrored?

Your RAM is almost surely fine.

Alternative theory: your RAID controller is failing. Try mounting the RAID set on the primary IDE channel if they're on a separate controller, or swapping in a new controller for the channel that has A and B.
posted by fourcheesemac at 8:01 AM on April 5, 2007

I've had similar problems on my Mac. It started getting very unstable and "freezing" for about a minute or two every 30 minutes or so.

Eventually, it got worse and wouldn't even boot. It turned out that I needed to replace the motherboard and hard drive. The RAM was fine.

Are you near an Apple Store? Do you have AppleCare? If so, just make an appt. at the Genius Bar and drop it off. They'll fix it in about a week.
posted by monarch75 at 10:51 AM on April 5, 2007

"Alternative theory: your RAID controller is failing"

There isn't one. It's software RAID.

I'd suggest swapping IDE controllers. Pull the "bad" drives off, put the "good" (C) drive on that IDE bus and see what happens. if the behaviour is erratic, then there's a chance that you found the problem.

What kind of Power Mac G4 is it? Apple made quite a few revisions to the G4 series, y'know... :-)
posted by drstein at 2:27 PM on April 5, 2007

Alrighty, got home after starting an install onto drive B, which failed too.

So, so far, installing tiger onto drives A or B (which are no longer in a RAID array, though drive B still has softraid, and the only copy of all of my data on it). Drive A might be failing, but two drives failing at the same time (but neither showing any S.M.A.R.T. status problems or any other drive test problems) seems a little unlikely.

Will first try the install again after removing 2 of the ram dimms, then start playing with the IDE controllers.
posted by anonymoose at 4:43 PM on April 5, 2007

G4 Dual 1GHz Mirror door drive
posted by anonymoose at 4:43 PM on April 5, 2007

Playing with RAM has revealed not only that one of my ram dimms was hosed, but also that the slot it was in is also hosed (switched around chips until that was pretty clear)

Taking out that chip and not placing any other chips in that slot allowed me to successfully install Tiger on drives A and B. Here's hoping that's the end of my problems.
posted by anonymoose at 6:46 PM on April 5, 2007

Wow..so much for famous last words. Install went fine on drive A, and just failed on drive B...
posted by anonymoose at 6:47 PM on April 5, 2007

Like I said, one drive in the array is hosed. Bad RAM was a coincidence.
posted by fourcheesemac at 6:10 AM on August 26, 2007

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