Apple Mac Startup Disk Getting Full

Quite often when we're contacted for Mac Support on a poorly performing machine we generally see 1 or both of 2 things.  A lack of memory for the number of tasks a computer is performing, and the startup disk getting full.  We'll talk a little bit about the startup disk today.

Why should I be worried about this?

When a Mac startup disk is constantly full, the situation needs to be sorted out because this is when errors start to accumulate on the disk.  The drive will be working harder to fill the small nooks and crannies left on the full disk.... and you could imagine when the system needs to write to the disk or modify files during normal processes... if it can't due to space issues you are likely to start accumulating disk errors and inconsistencies.  Another side effect you will notice is constant spinning beach balling.  The system will run much more slowly when it's working harder to perform disk read and write activities.

Check your Mac's free space

There are a few things you can do to create some more free space on your disk.  First let's determine how much free space you have.  

1. Find your Mac startup disk in Finder
2. Right click on it or select it and press "Command-I" keyboard combination.
3. Look at the free space from the Get Info window.

Get Info Macintosh HD

Get Info Macintosh HD

I've always worked on a rule that your Mac's hard disk should have about 20% free space or more.  This will allow the disk to work with large file happily and avoid working too hard.

What can I do to free up some space on my Mac?

This might prove to be a much easier issue to tackle than you think with a couple of easy things you can do.

Empty the Trash

We are often deleting files from our Mac, but if we don't remember to empty the Trash deleting files makes no difference to our free disk space.

Archive unused files

Files you no longer use from day to day can be copied to a DVD, or external USB drive for storage and possible recovery later on.  Be sure to delete the files from your Mac system and empty the Trash when you are happy the files are now safely on the external media.

Move pictures or music and video files to another disk

The greatest space burglars on our Apple devices are pictures, music, movies, and TV shows.  Delete your movies you no longer use... these consume Gigabytes of data and may make all the difference.  If you've purchased them from the iTunes store and you want to download them later you can.  Your iTunes library and iPhoto or pictures can be located on an external drive also.

Delete unused applications

Applications these days can take up an awful amount of space on your Mac computer.  Look at applications like iMovie, iDVD and Garage Band that contain Gigs of data you may never use.

Upgrade your hard drive

You could always put a larger drive in your Mac.  This requires careful work to backup the current data and install the new disk with a clone of the original disk... or at least all of your data.  We supply hard disk upgrade services so please contact us if we can assist you with this.


It's very easy these days to fill your Mac system's hard disk.  Especially with faster internet connectivity and our desire for music, and movies.  A few simple steps can be taken to look after our Mac's hard disk, and keep it from becoming full and degrading performance.  Your Mac will thank you for it.