Are you getting a message on your Mac advising the startup disk is almost full, but can’t figure out what is taking up all the space? In this article we will examine how to find out and reclaim the space, so there is room for your data.
Step One: Which data types are taking up the space?
Go to the Apple Menu > About This Mac > Storage and see what category is consuming the majority of the space. If it is Applications, Documents, Movies, Music and Photos, proceed to Step Two. If it is the System and Backups (such as in our system below), proceed to Step Three.
Step Two: Use the storage management tools in MacOS to find and remove large media files you don’t need.
Click the Manage button in the window above and you will be able to browse the files on your Mac by type (Applications, Documents, Photos etc). The largest files will be at the top so you can easily tell if there are large media files which you perhaps weren’t aware of and can delete. If there are large files here which you don’t want to delete or move to external storage, but also don’t use too often, then the other option is to compress them by right-clicking on the file and selecting “compress”. The original can then be deleted and the compressed file can be uncompressed if/when you need it.
Step Three: Download DaisyDisk or another third party application to find other data using a lot of space.
System and backup files will not be visible via the MacOS storage management tools, so if these categories are consuming a lot of your Mac’s disk space third party tools will be required.
DaisyDisk is a useful and well polished application suited to this task. Although not free, there is a free trial available from the developer’s website which will likely be enough to help you narrow down the storage issue you are having on your Mac. There are completely free applications designed for this too, such as Disk Inventory X, however they were built for older versions of MacOS so outcomes may vary depending on the Mac you have. Our system did not work with Disk Inventory X.
Once DaisyDisk’s scan runs, you will be presented with a visualisation of what is using your Mac’s disk space:
If “hidden space” accounts for a lot (100GB+), as it does in the example screenshot above, this could indicate possible disk issues on your Mac. Skip to Step Four.
If /volumes/Data/ is using heaps of space, this is caused by Time Machine backups. These large directories under /volumes/Data/ can be safely deleted (first you will need to show hidden files in MacOS), however you will lose your local Time Machine backups. Any remote Time Machine backups on a Time Machine device or external drive will remain even if the local ones are deleted.
If neither of these are using much space, skip to Step Five.
Step Four: Repair your Mac’s disk volume
“Hidden space” in DaisyDisk usually covers system files which DaisyDisk does not have permissions to delete. There will always be some portion of your Mac’s disk consumed by hidden space, however if it is hundreds of gigabytes this indicates the system is keeping files when they are no longer needed or is miscalculating how much space files are taking up.
In some cases this can be rectified by running Disk First Aid in your Mac’s Disk Utility:
If this doesn’t work and you still have loads of “hidden space” try Step Five, otherwise you may have to reinstall MacOS to solve this issue.
Step Five: Clear System Caches
System caches are important to improve the performance of your Mac, however if you want to squeeze a bit more disk space out for something or if your system is taking up an unusually large amount of space the system caches can be cleared using a free third party application called OnyX.
Step Six: Remove PowerPC architectures and unneeded language files
Another way to squeeze some more space from your system is to download a free application called Monolingual, which allows you to remove PowerPC architectures and language files, which most people don’t need. Monolingual can be downloaded from Github.
So what are PowerPC architectures and should you remove them? These are architectures are the ones used more than a decade ago, before Macs switched to Intel processors. Therefore if you only use only modern, frequently updated applications on your Mac you should have no need to keep these architectures (be sure to keep the Intel ones though). On the other hand if you use older, unsupported applications that may be built to run on both PowerPC and Intel Macs, it might be best to leave these legacy architectures in place, as once you remove them the only way to get them back is a fresh MacOS install.
As for language files, you can simply remove any languages which you will never need to use on your Mac. By default some commonly used languages such as English, French and Japanese are left in, however if you are unsure whether you will need a particular language or not it is best to keep it, as once removed you will need to reinstall MacOS to get it back. Fortunately most of the languages are slight variations on the main ones, so these can be removed without any worry.
Step Seven: If you own a MacBook with a SD card reader, use a MicroSD shortening adaptor to increase storage space with no change to weight or form-factor of the laptop.
This one isn’t a way to free up space on your Mac’s internal drive, however if you happen to own a MacBook with a SD card reader built in then you can increase total storage capacity significantly without any cost in terms of your MacBook’s portability.
You can achieve this using a regular MicroSD card combined with a MicroSD shortening adaptor. A shortening adaptor is simply a MicroSD adaptor short enough so that it doesn’t stick out of your MacBook:
The storage on the MicroSD won’t be as fast as your Mac’s internal storage of course, however it would be perfectly suited to storing large media files — movies, TV shows etc, where speed isn’t a critical factor.