OS Extended vs OS Extended (Journaled)

superspiffy

macrumors 6502a
Original poster
Feb 6, 2007
736
0
What's the difference between Mac OS Extended and Mac OS Extended (Journaled)? Which one is better to format an external hdd that's going to be use mainly as a scratch disk?
 

iBookG4user

macrumors 604
Jun 27, 2006
6,596
2
Seattle, WA
Journaling is a technique that helps protect the integrity of the Mac OS Extended file systems on Mac OS X volumes. It both prevents a disk from getting into an inconsistent state and expedites disk repair.

Journaled is a bit slower than non-journaled, though.
 

creator2456

macrumors 68000
Jul 10, 2007
1,648
2
Chicago
I have always been under the impression that OS X keeps a log file of where everything is located on the HD in Journaled so it can access it faster after multiple uses. i.e. Calculator taking 5 dock bounces the first time you use it and only 3 the next and .5 the third+
 

SC68Cal

macrumors 68000
Feb 23, 2006
1,642
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I have always been under the impression that OS X keeps a log file of where everything is located on the HD in Journaled so it can access it faster after multiple uses. i.e. Calculator taking 5 dock bounces the first time you use it and only 3 the next and .5 the third+
No, that's your system memory. That's what that big blue chunk called 'inactive memory' in the Activity Monitor pie chart. Stuff that you quit doesn't immediately get sent back to the disk, because it's much easier to keep it in RAM then make computationally expensive calls to put it all back on the disk, then have it get opened a few minutes later.

You're pretty close though. HFS volumes use an internal catalogue that consists of CNIDs, which list where files exist on the physical disk. Journaling plays a part in this because CNIDs are one of the weak points of the HFS system. If that catalog goes, there goes your disk, you're going to be spending some time rebuilding it.

http://docs.info.apple.com/article.html?artnum=107249
 

DEXTERITY

macrumors 6502a
Aug 14, 2004
577
58
to add on to the question. I think I normally initialize my internal hard drives as OS Extended Journaled. Is this a bad thing? I have a new drive I am simply going to store data on or use as a back up. Should I select Extended Journaled or simply Extended? I'm not sure if choosing one or the other damages the hard drive or shortens the life of it?

Thanks in advance
 

larkost

macrumors 6502a
Oct 13, 2007
536
1
The performance difference between Journaled and non-Journaled is really trivial for almost all workloads. And since the performance and safety difference is quite large when you run into problems, it really is worth sticking with the default (Journaled) unless you know you need something else.
 

typeadam

macrumors 6502
May 16, 2010
250
5
10016
Don't mean to resurrect this thread but one more question on top of this. Should I do Journaled on an external drive which will have 1 NTFS partition and one HFS+ partition?