Deleted 2 big user accounts. Now defragmenting?

mostly harmless · 01-23-2013, 09:59 AM

I just deleted 2 big user accounts (600GB).
Both are FileVault protected and after an incident of a system freeze and hard reset (switching off) I had regular kernel panics whenever I logged off from one of those accounts.
Now I wonder if I should leave the Mac on overnight to let it to maintenance like defragmentation before I copy the backups back onto the internal drive maybe tomorrow.
Maybe the maintenance can also be started with terminal –I guess so.
The question is wether or not it makes sense in the first place.

benwiggy · 01-23-2013, 10:07 AM

As far as I know, OS X does not do defragmentation of delete files. There's no point. The space is free to be written over.
OS X includes defragmentation routines at the time when blocks are WRITTEN, but that's it.

If you're talking about the periodic daily, weekly and monthly scripts, then they are mostly concerned with deleting temp files and stopping log files from getting too big. The weekly script also rebuilds the locate database.

If the Mac isn't on when the periodic scripts ares et to run, they will be run at the next available opportunity. And there are benefits from shutting down and restarting afresh, so you could turn the machine off and restart in the morning.

mostly harmless · 01-23-2013, 10:58 AM

Thank you Ben.

acme.mail.order · 01-23-2013, 05:55 PM

HFS, in general, does not need defragmentation. There are exceptions, like extensive video editing or software development (big stuff, like OpenOffice) but for the average user it takes care of itself.

After a big deletion like yours it might make sense to linearize - clone the drive to an external, format the original, clone back. This also clears up any directory corruption. Very important, however, that you do a file level clone with something like Carbon Copy. A block-level clone in Disk Utility also copies the problems.

This method is a lot less wear and tear on the drive than a traditional defragmentation.

None of the above applies if you have an SSD. Fragmentation is irrelevant when the latency time is zero.

01-23-2013, 09:59 AM	#1
mostly harmless Triple-A Player Join Date: Mar 2009 Posts: 97	Deleted 2 big user accounts. Now defragmenting? I just deleted 2 big user accounts (600GB). Both are FileVault protected and after an incident of a system freeze and hard reset (switching off) I had regular kernel panics whenever I logged off from one of those accounts. Now I wonder if I should leave the Mac on overnight to let it to maintenance like defragmentation before I copy the backups back onto the internal drive maybe tomorrow. Maybe the maintenance can also be started with terminal –I guess so. The question is wether or not it makes sense in the first place.

01-23-2013, 10:07 AM	#2
benwiggy League Commissioner Join Date: Aug 2006 Posts: 5,039	As far as I know, OS X does not do defragmentation of delete files. There's no point. The space is free to be written over. OS X includes defragmentation routines at the time when blocks are WRITTEN, but that's it. If you're talking about the periodic daily, weekly and monthly scripts, then they are mostly concerned with deleting temp files and stopping log files from getting too big. The weekly script also rebuilds the locate database. If the Mac isn't on when the periodic scripts ares et to run, they will be run at the next available opportunity. And there are benefits from shutting down and restarting afresh, so you could turn the machine off and restart in the morning. Last edited by benwiggy; 01-23-2013 at 10:09 AM.

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01-23-2013, 10:58 AM	#3
mostly harmless Triple-A Player Join Date: Mar 2009 Posts: 97	Thank you Ben.

01-23-2013, 05:55 PM	#4
acme.mail.order League Commissioner Join Date: Sep 2003 Location: Tokyo Posts: 6,045	HFS, in general, does not need defragmentation. There are exceptions, like extensive video editing or software development (big stuff, like OpenOffice) but for the average user it takes care of itself. After a big deletion like yours it might make sense to linearize - clone the drive to an external, format the original, clone back. This also clears up any directory corruption. Very important, however, that you do a file level clone with something like Carbon Copy. A block-level clone in Disk Utility also copies the problems. This method is a lot less wear and tear on the drive than a traditional defragmentation. None of the above applies if you have an SSD. Fragmentation is irrelevant when the latency time is zero.