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ATPM 10.07
July 2004


How To



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How To

by Sylvester Roque,

What to Do When You Need a Little More Room

Last month, as the rest of the editorial staff was putting the final touches on another stellar issue, I was struggling with some work-related deadlines. In the few moments I took off for fun, my iBook decided to assert itself and prove which of us was boss. Usually a rock-solid workhorse, it suddenly began balking at the more intensive tasks. Near-crashes and a kernel panic or two were involved. It was close for a while there, but I finally regained the upper hand.

In reality, it did not take too long to sort out the problem and the techniques that I used were simple. Many of you will consider them too simple for a column such as this; however, since I had forgotten these pearls of wisdom, chances are others have as well.

The Problem

Even during its worst temper tantrum, my iBook performed well. Its DVD drive no longer works, but that is not much of an issue since I have an external CD-RW drive that I can boot from when necessary. It continued to crank out word processing files, read e-mail, and view smaller graphics files without missing a beat. Nevertheless, all was not well in my little corner of the world.

The first problem that I noticed was Photoshop complaining about scratch disks being full. That was not much of a problem: I had forgotten to connect the external drive that I use for Photoshop’s scratch disk. The more troubling problem was that sometimes, in the middle of some intensive task, the Finder would complain about low memory and warn me of dire consequences if I didn’t act immediately. The system didn’t crash during those times, so a quick restart left me happily computing again, only to have the problem rear its ugly head again several days later. Lack of memory did not seem to be the problem; after all, I had used this same system to perform the same tasks several times. About the third time it happened, I took the time to troubleshoot and solve this problem.

The Cause

After a bit of detective work I was able to resolve what had appeared to be a random problem. The first clue was that these problems always occurred either in Photoshop, or in iTunes while converting music files. This was unusual since neither program had a history of such behavior. Upon closer inspection, I discovered that the problem always occurred while working with large files or large numbers of files. Apply a filter to an eight-by-ten photograph or convert several albums purchased from the iTunes Music Store, and boom. No crash, just dire warnings of things to come. From these clues, some of you already have a culprit in mind. Everyone else can keep reading.

On a good day, my iBook’s boot partition has about two GB of available space. That sounds like a lot, until you realize that OS X makes extensive use of swap files. If you are not familiar with swap files, think of them in much the same terms that you would OS 9’s virtual memory files. In both cases, by default these files can be found on the boot drive or drive partition.

For our purposes, there is an important difference between these two types of files. While OS 9 allowed you to control the size of virtual memory files manually via the Memory control panel, OS X controls the sizes of these files dynamically. If you do not have enough free drive space, the Finder will complain.

In addition to the Finder complaining, most applications that make extensive use of temporary files will also begin to complain. The only reason I had not noticed until now was that I had not spent enough time with these applications recently; this would explain why neither Toast nor iTunes wanted to convert the music files in my library. I could convert a few at a time, but the minute I ran low on drive space for temporary files there was a general complaint heard throughout the land.

A quick glance at my hard drive revealed that at the time the problems started, I had about half a GB of free space on the drive. For some reason, a song about needing elbow room kept running through my head (I think that’s from Scholastic Rock). That settled it: something had to go. A larger drive just was not in the budget. I had already moved Photoshop to an external drive, and at first glance I could not see anything else that would free up enough space to make a difference.

The Solution

The first step is to get rid of large files that you no longer need. You could spend your time searching for these files manually but that would seriously interfere with time better spent enjoying your Mac. Why not let a utility do the job for you? OmniDiskSweeper searches a hard drive and shows you a list of all files and folders ranked by size. You may then delete files you no longer need. With the free version, you must delete the files manually. Paying the $15 purchase price enables the delete button. This option has the added advantage that OmniDiskSweeper will not let you delete system files.

For many users who still need additional space the answer is simple. Move some data files to another location. Under OS X, many applications encourage you to store data inside subfolders in your home folder. Word processors, for example, may default to the Documents folder inside your home folder. By navigating through the Save As dialog box you can choose to save files in another location if you wish. I have never been in the habit of storing data in my home files so that was not an answer for me. It may also not be the best option in a multiple user setting.

One day, during my third attempt to finish converting the files in my iTunes Music folder I realized that these were the only type of data files stored inside my home directory. Performing a quick Get Info on my Music folder revealed that several albums located therein were consuming well over one GB of precious hard drive real estate. Those files had to go.

I was able to burn these albums to a CD and remove them from my hard drive. This of course meant that playing the files back on the computer was only possible when I had access to the CD. This was at best a temporary solution, and sure enough after a recent downloading spree at the iTunes Music Store I was once again faced with the need to move music files off my primary drive.

This time I found a different solution. I used a small external hard drive, but this should also work if you move the folder to another internal drive or partition. The basic steps to accomplish this are as follows:

  • Use a disk utility to check the health of the drive or partition that will house your new music folder. This is mainly a precaution, but there is no point putting the folder on a bad drive.

  • Go to your home folder and locate your iTunes Music folder. Copy the iTunes Music folder to its new location. In order to avoid any problems I made sure to use a utility that is aware of OS X file permissions: there are several such utilities out there, but I used Carbon Copy Cloner.

  • Once you have successfully copied your iTunes Music folder to its new location, make an alias of that folder. Do this by selecting the folder (in its new location), and either select “Make Alias” from the File menu or press Command-L. Delete the iTunes Music folder within your Home folder, and replace it with the alias that you just created. Be sure to remove the word “alias” (including the space character in front) from the alias file name.

  • The last step is to launch iTunes and tell it where its new Music folder is located. In the current version of iTunes, you can do this by launching the program and pressing Command-Comma to open the Preferences dialog window. Once there, click on Advanced. You will see the pathname to the old music folder location. Click the “Change” button, and you will have an opportunity to select your iTunes Music folder in its new location.

I am unsure whether the step of creating the alias is necessary; I did it mainly so that I would not look there one day and wonder where the music files were.


If a lack of drive space is causing you some problems and a larger hard drive is not practical then these techniques may help. I have listed them in the order that seems to be most beneficial.

Without running any applications that use temporary files or scratch disks, see how much free drive space is available on your boot drive. If there is not very much space then it might be time to move some data files to a new location. When you do this, use a utility that preserves file permissions.

If you seem to have enough space on the boot drive and the problem only affects certain programs, tackle the problem that way. Launch each program and see if there is a preference that controls how large the temporary files are or where they are located.

Theoretically, the techniques applied to the iTunes Music folder should work with other types of data as well. Which folders you need to move will depend upon the type and size of the documents that you create. Keep track of the original locations for any folders that you relocate, as it may prove necessary to relocate them back.

Be aware that if you move any files to an external drive, then that drive must remain switched on, attached to your computer, and made available to the Finder for its files to be available. Depending upon which files you have moved, some programs may not function correctly of they are unable to access necessary files.

Although I have seen procedures to move OS X’s swap files to new locations, there appear to be numerous problems or side effects that can occur as a result. The same can be said for moving the entire Users folder to a new location. If the steps I have outlined have failed to free up enough space to resolve the problem and you have enough RAM installed for OS X to function acceptably, then either something else is going wrong or it’s time to buy a larger hard drive.

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