You can employ any of the following tips to increase the free space available on your Mac OS X startup disk without altering your hardware. In the General pane, the Capacity, Available (free space), and space Used on your startup disk will be displayed, as seen in the following screen shot: The Get Info window for your startup disk will open.Press the Command-I keyboard combination.In Finder®, select your startup disk's icon.To check how much free space is available on your startup disk: Determining available space on your startup disk Additional tips are provided for saving more space if you have a second internal hard drive or an available partition. While you could replace your current hard drive with a larger model, or install a second internal hard drive if your Mac will support such, the following tips will help you to free some space without changing your hardware. This extract from a chapter of our book Troubleshooting Mac® OS X describes several ways to free-up space on your Mac OS X startup disk, also known as your Mac OS X boot volume.
Freeing space on your Mac OS X startup disk