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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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