Defrag Questions...

You don't need to defrag on Mac OS X, except possibly when partitioning a drive.

About disk optimization with Mac OS X

Five Mac maintenance myths

 

In my experience there are situations where an OS X drive can become severely fragmented.

The Macworld article referenced previously states that routine defragmentation is not required. It goes on to say:

File fragmentation is an issue primarily for people with almost-full hard drives and people who work with very large files or large amounts of data (for example, video and some image files). If your drive is almost full, a better option is to free up space or upgrade to a larger drive. People who truly need to defragment—or optimize, which is defragmentation that also attempts to position particular types of files for optimal performance—can use utilities such as Prosoft Engineering’s $99 Drive Genius 2 or Micromat’s upcoming $98 TechTool Pro 5. (You may also hear about directory fragmentation. This is different from file fragmentation, and is addressed by utilities such as DiskWarrior.)

You can download and run iDefrag to see if your drive is indeed fragmented. If so, you can pay for a license and fix the drive. iDefrag costs $30.95. It's the least expensive software that I know of.

You can also create a bootable clone of the drive, reformat it and copy the data from the clone. The result will be an unfragmented drive. But it won't be optimized like it would be if you used iDefrag and similar utilities.

iDefrag http://www.coriolis-systems.com/iDefrag.php

Macworld UK Review http://www.macworld.co.uk/digitallifestyle/reviews/?reviewid=3228570

 

"What's a good, cheap defrag utility?"

iDefrag is one.

I also use the defragger that's a part of the "Drive Genius" suite of tools.

You will be told again and again that "you don't need to defrag".

That is nonsense. Yes, OS X does re-concactenate some fragmented files, but not all of them. To make matters worse, the OS does NOTHING to reclaim small "fragments of space" throughout the drive. If you use a defragger, and examine the sectors of the drive before you actually defrag, you will see how disjointed the surface of the drive actually becomes. Defrag and optimize it, and you'll have a large, contiguous portion to which large files may be moved/copied.

This is particularly important if you handle video and audio files.

 

As usual, I have to agree with GGJstudios, over the past 10 years with Macs as primary machines in my housewolds, I've never seen anyone defrag or need to defrag a Mac.

 

When I was having issues with my early 2008, i thought it could be drive related as well. I downloaded the iDefrag and it allows you to assess your drive before purchasing to actually perform the defrag. The only time I shut down or reboot is when needed during an install or system requirement or if the battery died accidentally It had been running essentially for almost 3 years constantly and the drive was only like 4-5 percent fragmented (and I move lots of data everyday and am constantly adding and removing vm images for work), as reported directly by iDefrag and the application even suggested I not defrag. Saved me seem money and helped me be more trusting of OSX (as coming from Windows I had to defrag at least once a week).

 

The "no need to defrag" myth has to be the biggest that there is about Mac OS. What Fishrrman has said is correct.

 

Note the bolded part. If your disk is within, say 75-80% of its full capacity, you should seriously consider getting a bigger disk. Defragging at that point is just rearranging deck chairs on the Titanic.

Getting a big scratch drive may also a good option if you "work with very large files or large amounts of data (for example, video and some image files)" Keeping that stuff off your system drive can be a big help.

 

While I basically agree, your 75-80% rule of thumb is rather conservative. (And I think that the Titanic analogy is rather silly...) I'd say that is the time to start thinking about getting another drive; once you reach 10% you should have another drive up-and-running.

Designating a separate scratch partition on an external drive is a good way to minimize fragmentation on drives. The Adobe website has suggestions for scratch partition sizes based on the average size of the files the user typically edits.

I really don't understand the folks who insist that OS X never needs defragging. Sometimes it does and sometimes it doesn't; there is no correct answer that applies to everyone. Since it is easy and free to analyze a drive, the simple answer is to run a utility and find out what is up with the drive. Then proceed accordingly...

 

iDefraged

OS X does a good job keeping file fragmentation under control. However, I did get some speed improvements with iDfrag.

My time machine backups were running very slow. TM updates were taking 10 minutes to run, even when no files were modified. (If I selected backup now 2 times in a row each time it would take around 10 minutes)

I had been thinking my catalog B tree or whatever that is needed to be rebuilt. I always had a decent amount of free HD space, but between multiple VMware virtual disk, and lots of other files large and small coming and going, I think something got out of whack.

So I bought and ran iDefrag. Took like 10 hours to run but there was an improvement! Time machine updates now complete within a minute. Boot time also improved from 45 seconds to 34.

B


http://www.coriolis-systems.com/

 

Once I had trouble creating a partition for Bootcamp when I had to resort to iDefrag to defragment the drive myself. No matter how much OSX does its own defragmenting, there will be a point when it's beyond its own capabilities.

 

In general OS X doesn't need to have its filesystems defragmented. There are some good examples above of why it isn't needed in general with one good example of when it was needed.

If you run a filesystem near 100% full and constantly delete and create files, you could run in to a situation where the disk needs to be defragmented. It depends on the size of the files in question.

The best suggestion above was to use iDefrag for free to see how fragmented the disk is before paying for a utility you might not need.