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A possible fix for 'overlapped extent allocation' errors
Authored by: sumnchai on Mar 04, '03 11:30:28AM

i'm kinda mad...long story short, i had an OEA and when i called apple, they said that the only way to fix it was to wipe the hard drive and reinstall OS X - and this was from an senior tech. if this works, consider my faith in the apple tech help severely damaged.



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A possible fix for 'overlapped extent allocation' errors
Authored by: terceiro on Mar 04, '03 11:38:51AM

If it works, I'm mad too. I just had to go through that whole rigamarole -- neither Disk First Aid (on the OS X disks) nor Drive10 couldn't repair it. I wiped and reinstalled -- and spent two full days doing it. Sigh.

Next time I'll know.



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A possible fix for 'overlapped extent allocation' errors
Authored by: ahknight on Mar 04, '03 12:04:57PM

I don't see why you'd get mad at them. They're not there to go kernel-hacking for you, just explain how to get iTunes to stream. Technical support is granny-support, not power-user support. Power-user support is called "consulting." :)



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A possible fix for 'overlapped extent allocation' errors
Authored by: osx_4me on Mar 05, '03 11:39:47AM

AMEN !

This is true for the first-line support at any computer company, folks.

That's what we're here for. If the posted fix works, submit it to Apple at http://www.apple.com/macosx/feedback/
They just might post it as a knowledgebase article. For the record, any command-line level fixes are very likely going to be outside the realm of knowledge for any first-line support folks at Apple, and we should probably suspect that those folks are in fact told to NOT stear Granny (or any other caller) in that direction.



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A possible fix for 'overlapped extent allocation' errors
Authored by: saint.duo on Mar 04, '03 12:40:08PM

It won't always work. Sometimes those overlapped files are core system files. The best overall fix is to nuke and reinstall.

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duo



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A possible fix for 'overlapped extent allocation' errors
Authored by: smkolins on Mar 04, '03 01:44:49PM

I agree. There is actually nothing new here. If you happen to know or figure out what's crosslinked you could always delete just those parts and ussually recover pretty gracefully. Figuring out what's crosslinked may be hard. In this case he just guessed and guessed correctly.

This just underscores one thing about the OSX force quit process. Yes the ram/active OS may be ok, but no there's no gaurantee the hd is.

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Steven
smkolins@mac.com
http://homepage.mac.com/smkolins
Possess a pure, kindly, and radiant heart!



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A possible fix for 'overlapped extent allocation' errors
Authored by: Gus on Mar 04, '03 03:45:06PM
Would turning on journaling help Disk Utility and/or fsck in fixing these problems? Just a thought ;)

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Ing. lic. G.E.A. Vansteelant
Lead Assessor

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A possible fix for 'overlapped extent allocation' errors
Authored by: smkolins on Mar 05, '03 08:26:29AM

Interesting thought....

I'ld like to see some experiments.

However until then... my thoughts are... that it would still crosslink. Journaling does check the sanity of the requests for allocation as far as I know. It just checks that they were accomplished. Still I suppose it's possible journaling would read the incoming requests as undelivered and not execute them, or delivered, find them unfinished, and execute them correctly at boot.

Definately need to test this!

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Steven
smkolins@mac.com
http://homepage.mac.com/smkolins
Possess a pure, kindly, and radiant heart!



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A possible fix for 'overlapped extent allocation' errors
Authored by: tanvach on Mar 05, '03 04:41:13PM

I have had my harddisk journaled since 10.2.3, but the number of the overlapped extents had gone up since then. There used to be about 4, now there are 10!

Tan



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A possible fix for 'overlapped extent allocation' errors
Authored by: lamon on Mar 05, '03 05:20:56AM

From what I know, HFS+ is fragile when the disk is filling up too much. You do not risk this problem unless you go over 85% occupation of the disk (note that UFS on Unix usually reserve 10%). The main cause I have seen for this is usually the swap file growing up and filling the partition (could also be a runnaway log) and a lot of other problems are due to this, like corrupted or diseappearing preference files.

So the best idea is to create a separate partition for swap files, and maybe log files also if you are running a server. I have that set-up and never had a problem in 18 months of use of OSX.

If the problem happens, you have two files referencing the same extend. The problem is that you do not know to which file the data in the extend belongs to. If the overlapping files are user file, you can copy them, delete both originals and you should be OK. If the overlapping files are system files, you may disrupt the system and be unable to reboot by removing them. In that case, I would boot on another disk or a bootable system CD, surgically remove these files and create a new copy from the working drive or CD. Otherwise, reinstall.



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A possible fix for 'overlapped extent allocation' errors
Authored by: smkolins on Mar 05, '03 08:29:08AM

I agree about the problems of filing the hd, and while it could be because of the swap file(s) I think it's more likely that the system will go nuts trying to find unfragmented space (or actually give up) and fragmentation on the most recent files will go through the roof.

See man tunefs.

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Steven
smkolins@mac.com
http://homepage.mac.com/smkolins
Possess a pure, kindly, and radiant heart!



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A possible fix for 'overlapped extent allocation' errors
Authored by: lamon on Mar 05, '03 08:45:43AM

True. But usually, the system fails to find space because the HD is full, and I think that one of the main causes of accidental fill-up is a runaway swap. If you keep 85% free, you should have no problem. I have been up to 95% on an archive partition (large files only) without problems either.

I can't check here at work but is tunefs relevant to HFS+? I throught it to be a FreeBSD/UFS manpage.



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A possible fix for 'overlapped extent allocation' errors
Authored by: smkolins on Mar 06, '03 10:16:06PM

Perhaps. I'm seeing lot's of references to bunches of OSes - linux, BSD, HPAUX... I'm seeing references to hfs modifications....

Nothing direct yet, but I know the command iostat wasn't enabled correctly in 10.0 or 10.1 but it works in 10.2....

tunefs might be there but not exactly reachable....

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Steven
smkolins@mac.com
http://homepage.mac.com/smkolins
Possess a pure, kindly, and radiant heart!



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A possible fix for 'overlapped extent allocation' errors
Authored by: sidharthamacdoc on Apr 16, '03 05:54:28AM

I suffered the dreaded OEA error when my HD was only
20% full! Contrary to most of the threads of the error
occuring when the HD is over 80% full.

Makes me kinda weary whenever I install apps or if the app
generates cache files.

As I am new to OSX, how do you move swap files to another
partition? I know how to do this in Netscape and
Photoshop, but the others, like Safari etc?



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