Should I Defrag my Mac?

Recently, the Mac Pro at our studio has been a bit temperamental. Pro Tools sessions can take 5-10 minutes to load (usually less than 30 seconds), programs hang and sometimes can’t be killed with force quit, and things are generally a bit sluggish. If I had been on a Windows machine, I would have done what I did countless times with Windows 98, 2000, XP: virus scan, disk cleanup, adware removal, registry clean, defrag, scandisk, and as a last resort, reinstall the OS. But on a Mac, what to do? All I’ve ever had to do with my personal Mac machines is free up some hard drive space. Defrag a Mac? Nahhh.

From an Apple Support article entitled “About disk optimization with Mac OS X“, it would seem that disk defragmentation isn’t necessary on a Mac.

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.

If you can read further down without feeling guilty for not trusting the Apple geniuses who wrote the article, you’ll come across a sentence that reads: “If your disks are almost full, and you often modify or create large files, there’s a chance the disks could be fragmented. In this case, you might benefit from defragmentation, which can be performed with some third-party disk utilities.”

Depending on the audio quality you’re recording with, a single take of one instrument for an average 3 minute song can create a file that’s 50-100 MB. That’s just one track. Our sessions can get above 60 tracks. Granted, audio files are significantly smaller than video files, but probably still fit the definition of “large” files in the context of the Apple Support document.

In looking for more information about the Mac-defrag question, I came across a Digg article page with hundreds of comments going back and forth about the value of defragging a Mac. The general consensus is no, it’s not necessary, but if you’re using large files regularly, like audio and video, you have to defrag regularly. (Note that the actual article link is wrong, but the comments are still valid.)

Ken from Soundstep Productions, who shares the studio building with us, thought the drives needed defragging, or possibly replacing, since they’re a ~2 years old and have been used fairly heavily for the past year. Our “session” drive where all of our audio files are stored took about 7 hours to defragment with iDefrag. The system drive, however, has been defragging for over 12 hours and appears to be only about 30% complete. There aren’t any sessions on that drive, so the number of “large” files is minimal. I reckon the system drive is on its way out, but we’ll find out when the defrag finishes. Ken suggested we swap out the drives regularly anyway, as they’re getting so cheap. It’s not worth risking a failing drive, even with good backups – the recovery time could cost us a project.

In conclusion, if you are doing audio or video with your Mac or handling large files (20mb+) regularly, you might want to try defragging if you see a drop in performance over time. If you’re not doing anything like this, don’t bother.

Update: After defragging for over 36 hours, I decided to swap out the system drive we’ve been using.