Disk defrag ?'s

me399 · Mar 8, 2008

I know on windows this is something built into the O.S. and you should run it ever once and a while to keep the H.D.D. in order and neat, is this something that is also built into O.S.X tirger and does it need to be run. I have 80 gigs of stuff on my MBP, I know if this was a windows machine it would be a mess and in dire need of defragment. I dont know if O.S.X. works the same way, if so and I need to Defrag, is this feature built into Tiger, if so where do I find it, if not what should I download?

louishen · Mar 8, 2008

No - OSX does the drefrag in the background without you needing do do a thing

goobimama · Mar 8, 2008

While OS X (HFS+) is far superior to Windows (FAT or NTFS), defragmenting still helps. I've noticed difference in performance using iDefrag. Some say I'm delusional but I will stand by it. However, once in six months or so is more than enough.

cwa107 · Mar 8, 2008

Apple's position on defragmenting (FWIW):

http://docs.info.apple.com/article.html?artnum=25668

christm · Mar 8, 2008

From apple

Do I need to optimize?

You probably won't need to optimize at all if you use Mac OS X. Here's why:
Hard disk capacity is generally much greater now than a few years ago. With more free space available, the file system doesn't need to fill up every "nook and cranny." Mac OS Extended formatting (HFS Plus) avoids reusing space from deleted files as much as possible, to avoid prematurely filling small areas of recently-freed space.

Mac OS X 10.2 and later includes delayed allocation for Mac OS X Extended-formatted volumes. This allows a number of small allocations to be combined into a single large allocation in one area of the disk.

Fragmentation was often caused by continually appending data to existing files, especially with resource forks. With faster hard drives and better caching, as well as the new application packaging format, many applications simply rewrite the entire file each time. Mac OS X 10.3 Panther can also automatically defragment such slow-growing files. This process is sometimes known as "Hot-File-Adaptive-Clustering."

Aggressive read-ahead and write-behind caching means that minor fragmentation has less effect on perceived system performance.

For these reasons, there is little benefit to defragmenting.

Note:Mac OS X systems use hundreds of thousands of small files, many of which are rarely accessed. Optimizing them can be a major effort for very little practical gain. There is also a chance that one of the files placed in the "hot band" for rapid reads during system startup might be moved during defragmentation, which would decrease performance.

Lifeisabeach · Mar 8, 2008

And here's another take on defragging:
http://www.macattorney.com/ts.html#Anchor-Note-51722

I recommend reading this. It seems to be a pretty credible article on drive maintenance in general. The bottom line on defragging is "it depends". I saw a significant difference when using iDefrag the first time I used it... not quite so much since. It much depends on how the computer gets used.

EDIT: Here's another nice techinical write-up:
http://www.macfixit.com/article.php?story=20070301091515843

jayman414 · Mar 8, 2008

christm said:
From apple

thanks for highlighting the important stuff. I was under the impression that defragging did little for Macs and this just confirmed it. Thanks

christm · Apr 13, 2008

thanks. although someone, obviously didn't approve of me being helpful by highlighting what apple says, as someone has used the rep tool against me.

why !. Im helping.

bobtomay · Apr 13, 2008

christm said:
thanks. although someone, obviously didn't approve of me being helpful by highlighting what apple says, as someone has used the rep tool against me.

why !. Im helping.

takes all kinds christm - don't sweat it - and remember if it's a gray blip, just means they haven't been around long enough for their rep to count, for or against.