Byte breakdown

One of the questions I’m frequently asked as a Mac writer—and a question we see quite often in the Macworld forums —is, “My hard drive is getting full; how can I see which files are taking up all that space?” It’s an understandable question: Your hard drive started out with 50GB or so of free space, but now it’s down to 10GB and you have no clue as to why. (OK, so you’ve installed a few sizable software packages, and then there are all those MP3 files you ripped from your CDs and media you purchased from iTunes, and...)

Although you could manually browse your drive, using the Finder’s “Calculate all sizes” view option, to see which folders are taking up the most space, then delve down into the biggest ones to search for large files and folders hidden inside, and so on, an easier approach is to use a utility that shows how your hard drive space is being used.

WhatSize

One of my favorite such utilities is ID-Design’s free WhatSize 10.3.9 (   ). When you launch it, you see a list of all mounted drives; click on one, and WhatSize scans all the files on it. (How long the process takes depends on the drive; for my 128GB boot drive, containing approximately 101GB of files, it took WhatSize just a few minutes to complete the scan.) When it’s finished, WhatSize automatically sorts all the files and folders at the root level of the drive by space used; even normally invisible files are displayed. Each file and folder is also color coded by size range: Sizes over 1GB are red, sizes from 1MB to 1GB are purple, and sizes below 1MB are green.

WhatSize

You can then browse those files and folders just as you’d navigate them in the Finder’s column view. (A list view option is also available.) As you do, the contents of each folder are, again, displayed in descending order of size. Through this process, you can quickly see which files and folders are occupying the most space on your drive. If you find a huge file that you want to delete, simply select it and click the Delete button in the WhatSize toolbar.

WhatSize also lets you examine the contents of just a particular folder—instead of an entire drive—by clicking the Folder button in the toolbar; click the Home button to examine just your Home directory.

But my favorite option is Table View. Available from the Tools menu, Table View lets you filter your results, displaying, for example, files and folders—or just file or just folders—anywhere on the drive larger than 1GB. This feature makes it much easier to find offending space-wasters, because you don’t have to manually search each folder on your drive. (Note that for some reason, Table View’s window is called FlatView.) By Control/right-clicking on a file in Table View, you can move it to the Trash or reveal it in the Finder. However, be aware that there is a rather serious interface bug in Table View: If you select a file in the list, then Control/right-click on a different file in the list to delete it via the contextual menu, the selected file, not the one you’re clicking on, will be deleted. Thankfully, a confirmation dialog appears pointing out which file will be deleted, but given that most people tend to click “OK” when they see a dialog, I consider this to be a serious bug. Be sure to select the desired file before Control/right-clicking on it.

The Tools menu also lists BarChart View and PieChart View; unfortunately, neither worked for me.

OmniDiskSweeper

A tool similar to WhatSize is Omni Group’s $15 OmniDiskSweeper 1.5 (   ). Like WhatSize, viewing a drive in OmniDiskSweeper displays it in column view, with files and folders sorted by size and color-coded (in this case, >1GB = bright purple, 1MB to 1GB = dark purple, 1k to 1MB = dark green, and 0-byte files = light green). Selecting a file and clicking the Delete button moves the file to the Trash.

OmniDiskSweeper

OmniDiskSweeper doesn’t have as many useful options as WhatSize, but it does have one unique feature: When you select a folder in the browser, OmniDiskSweeper lists, at the bottom of the window, any Mac OS X packages to which the files in that folder belong. For example, if you select the folder /Library/Application Support/iWork ’06, OmniDiskSweeper points out that this is “Part of package iWork,” so you know not to delete it if you actually use iWork. Or, for a more serious example, if you select /private/var/vm—a folder that on my system takes up 2GB of space—you’ll see that it’s “Part of package BaseSystem.” In other words, don’t even think about trying to delete it. (Not that OmniDiskSweeper would let you; see below. And if you're curious, that folder is where Mac OS X stores your virtual memory swap files.) Unfortunately, this feature works only if the files in question were installed by Mac OS X’s Installer utility and are cataloged in an Installer receipt package in /Library/Receipts. And if, like the Library folder displayed in the screenshot above, the folder contains files from many packages, the package names don’t fit in the OmniDiskSweeper window—even when the type is automatically reduced to near-illegible size.

GrandPerspective

If you’re a visual type, you’ll enjoy the free GrandPerspective 0.93 (   ), which I discovered thanks to Derik DeLong over on the MacUser blog. Instead of providing a list of files and folders sorted by size, GrandPerspective examines the volume or folder of your choosing and then creates a visual representation of the space occupied by each file on that drive or in that folder. (A similar utility called Disk Inventory X is also available, but I prefer GrandPerspective.)

GrandPerspective

By default, files are color-coded by directory—files of the same color clustered together are located in the same folder. But you can instead choose to have files color-coded by directory depth (so that all files at the same depth—say, two folders down—are the same color); by extension (so that all files of the same type are the same color); or by name (so that all files with the same or similar names are the same color). Clicking on a block displays the file name and path at the bottom of the window.

Although this visual approach may not seem as useful at first glance, so to speak, using GrandPerspective I immediately spotted something that I didn’t catch with WhatSize or OmniDiskSweeper: That big, purple blob of files on the left side of the screenshot above, which represents over 7GB of video files. Turns out that the EyeTV 200 I was testing as a way to get TV shows onto your iPod first converts shows from EyeTV format into .m4v format, placing the converted files in your Movies folder, and then transfers those video files into iTunes—without later deleting the files in the Movies folder. So I had 15 large video files taking up a huge chunk of space on my drive, even though I’d already deleted the videos from iTunes. GrandPerspective also made me take a closer look at the big blue item just to the right of the purple blob; an old, bloated Entourage database that I forgot to throw away after cleaning out a bunch of old email and compacting. Deleting that freed up another 1.3GB. In other words, with a quick glance at GrandPerspective, I was able to find nearly 9GB of virtual litter on my boot drive.

As you’re browsing files in GrandPerspective, you can click the Down button to magnify the area around a selected block; in this way, you can dig down into those groups of files that are much too small to work with in full-drive view. However, this feature isn’t as useful as it could be, as I find it difficult to zoom in too far with any accuracy.

GrandPerspective

Unlike WhatSize and OmniDiskSweeper, GrandPerspective won’t delete files for you; however, when a file is selected in GrandPerspective, clicking the Open button reveals the selected file in the Finder where you can delete it yourself, if desired. (Hopefully the developer will label this button more clearly—for example, as Reveal —in a future version.)

Dangerous?

Luckily, none of these utilities will delete files for which you don’t have access, such as system files and files in other users’ Home directories. Of course, this also means that you can’t use these utilities to examine files and folders that you wouldn’t normally be able to browse in the Finder, so it’s possible that substantial chunks of your hard drive are being used, for example, by video and music files inside the Home folders of other users. (If you’re an administrator of a computer and have a legitimate need to browse for such files, you can launch one of these utilities as root via Pseudo; you’ll then have unfettered access to any and all files—and, thus, their sizes—on your drive.)

Choices, choices

Which do I use? For getting a quick overview of what’s using the most space on your drive, GrandPerspective is tough to beat: One look and you immediately see the largest files (and, in directory view, the largest folders). On the other hand, WhatSize is my favorite for getting a comprehensive overview of how my disk usage is distributed between the various folders on my drives; and its TableView filtering is a great way to quickly view a list of all files over a certain size. If you’re worried about accidentally deleting important system files, OmniDiskSweeper’s information display is helpful; but then again, so is the golden rule of computers: If you don’t know what it is, leave it alone.

Whichever you choose, you’ll likely find at least a few opportunities to clean house.

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