maintenace after power surge

Though there are various opinions on the effectiveness, I typically will follow a two-step procedure after an event like this, especially on critical computers:

1. Restart the computer in "Safe Boot" mode (hold SHIFT down while booting) which will force a directory structure check.

2. While in Safe Mode, perform a permissions repair in Disk Utility. Reboot normally.

would it be too late for me to run in safe boot?

I've had power outages before on my iMac, while running, and it started just fine (after un plugging it, and plugging it back in, somehow it won't turn on unless I do that)


Anyway, I did that, when I logged in, A lot of things were messed up. My iTunes Library was corrupted, Firefox lost all settings, including the skin I had (they were still installed, just not in use)

my iCal has been wiped, NetNewsWire lost all RSS Feeds, a torrent download disappeared (the files were still there), and who knows what else.

Any idea as to what happened? I think It might have happened when I rebooted while it was logging me in the first time, as it seems to have frozen

If you have journaling enabled on your Mac's Hard Drive the chances of loosing data is pretty small. To ensure that no data was corrupted, open Disk Utility, select your drive, and then choose "Verify Disk". This will scan your drive for errors and report to you if there are any.

I'd also zap the PRAM. I don't know about the technical merits of this, however. It seems logical.

Repairing Disk Permissions will NOT help you in this case. If you had installed some software that didn't clean up after itself, and left permissions out of order, repair permissions. But we need to look at what's storing the permission if the power is cut... and that means Verifying the filesystem is intact.

i.shaun said:

I've had power outages before on my iMac, while running, and it started just fine (after un plugging it, and plugging it back in, somehow it won't turn on unless I do that)
<snip>
Any idea as to what happened? I think It might have happened when I rebooted while it was logging me in the first time, as it seems to have frozen

Click to expand...

Start into Single User mode. It will give you a Terminal-style prompt. Type (no quotes!): "fsck -yf /" to run FileSystemCheck. the -yf means that it will respond Yes to any question to repair the drive, and Force the drive to be checked (usually, a journaled drive is assumed to be clean). The '/' means to use your internal hard drive.

If you look closely, right above the prompt is a line about mounting the hard drive and having to run fsck first. It gives you the command to run, right there. Just retype that command and press return.

Re-run until it says "Volume <<HDD Name>> appears to be OK." (or something nearly similar)

To get out of this mode, type "shutdown -r now" and your computer will restart.

Mechcozmo said:

If you have journaling enabled on your Mac's Hard Drive the chances of loosing data is pretty small. To ensure that no data was corrupted, open Disk Utility, select your drive, and then choose "Verify Disk". This will scan your drive for errors and report to you if there are any.

I'd also zap the PRAM. I don't know about the technical merits of this, however. It seems logical.

Repairing Disk Permissions will NOT help you in this case. If you had installed some software that didn't clean up after itself, and left permissions out of order, repair permissions. But we need to look at what's storing the permission if the power is cut... and that means Verifying the filesystem is intact.

Click to expand...

Thank you very much.

I ran a Repair on Disk Permissions anyway, Figuring it would do no harm to try. Despite the fact that there was no programs installing or anything during the power outage, there was numerous errors that it fixed.

I ran "Verify Disk" and got some errors, something about the disk label needing minor repair, and some other things. I booted into single-user mode and ran "fsck -yf /" and it told me there was many errors, including Unreadable disk sectors ranging from sector 16-31.

I ran "fsck -f" and it proceeded to fix the errors (from your description I thought it would have done that to begin with)

I booted back into OS X, and ran Verify-Disk -- everything is OK.

I should learn to backup my Calendar somehow, iTunes was recently backed onto 5 single-layer DVDs -- though with the new album art, and some corrected metadata, I believe I should make another backup.

Firefox wasn't a problem, even if I lost my bookmarks, I have them saved in a file. RSS feeds are easy to re-subscribe to, torrent was saved, keyboard maestro didn't lose it's macros, steel.app didn't lose my passwords. I consider myself lucky, as I didn't lose much, and even my iTunes music wasn't corrupted, only the iTunes Library file itself.

i.shaun said:

I ran "fsck -f" and it proceeded to fix the errors (from your description I thought it would have done that to begin with)

Click to expand...

You have to run it until it comes back clean.

Glad your data was all OK; might I recommend Time Machine, though?

How about investing in a $39 APC UPS down at Staples?

donmei said:

How about investing in a $39 APC UPS down at Staples?

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If the power outage lasts longer that 5-10 minutes, you have to plan for a graceful shutdown. Depending on the devices and the load on the UPS, that can be easier said than done. A momentary outage is easily handled, but anything longer can still damage equipment even with a UPS attached if the UPS is drained. Not all of the UPS devices you'll encounter even have the ability to communicate to the computer their status-- or they'll have a serial port, which is almost the same as not having anything.

while a power supply sounds good, it is expensive.

I never had a problem before with random shut downs in the past. I am confident that it had something to do with the fact that it appeared to freeze during log in. At that point I shut it off by holding the power button, then proceeded to power it back up and log in again.


Losing random settings, and files is all that happened, thankfully -- I was able to restore them all. I can understand losing a document as I work on it, if I forget to save it, or having a corrupted movie file if handbrake is in the process of doing something when the power cuts out -- and I am guessing that is the reason for the extra power supply.

A heads up is always useful, and can save you some headaches when working on documents, videos, pictures, or whatever you work on. Is that it's only purpose?

Does the mac losing power suddenly really damage equipement? I didn't think so seeing as it has happened numerous times without consequence (other than losing some un-saved text files)