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Question: How much hard drive space to leave free?

Hello, my Mac internal hard drive is 75 GB. I regularly use memory-greedy apps such as Photoshop and Illustrator to create and edit large graphic files. Also, I use Adobe Creative Suite 2 to design publications and will download CS4 very soon.

I use an external hard drive of 150GB to create and store all my working files, photos and music.

I've been told that I need to leave a certain percentage of free space on my internal hard drive for it to process optimally, but I cannot recall what that amount is. Is there a rule of thumb for this?

Right now there is only 19.7 GB free on my hard drive. Since I create and store all my files externally, I don't know what keeps eating up my internal hard drive space. Could it be application updates and upgrades?


Powerbook G4, Mac OS X (10.4.6)

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Feb 3, 2009 11:07 AM in response to Karen Simmons In response to Karen Simmons

Your Mac needs adequate hard drive space to operate normally. How full can a drive be before it's too full? There is no hard and fast rule that says “X” amount or “%” of free drive space is needed. A low amount of RAM requires more drive space for Virtual Memory’s swap files.

Problems from insufficient RAM and free hard disk space are discussed in this link

Here’s some general guidelines for minimum hard drive free space:
1. As a general rule, your available space should be 5GB as an absolute minimum as it generally requires that much free space to perform an Archive and Install of Mac OS X and still preserve some free space for VM swap files.
2. Some say that your hard drive should have at least 5% of it's capacity available for use. Still others say 10% to 15%. If you routinely process complex graphics and videos, even more space is required.

With your 19.7GB of free space, you should be OK. Usually it's best to not state a percentage, but state an amount of free space. There's a big difference in having 10% free space (20GB) on a 200GB hard drive compared 10% (4GB) to a 40GB hard drive.

Look at these links about freeing up more space.

Where did my disk space go?
Download & use WhatSize described in this link or Disk Inventory X @ http://www.derlien.com/

Freeing space on your Mac OS X startup disk

Amazing Disappearing Drive Space

Increase HD Free Space
http://macosx.com/forums/howto-faqs/275191-how-easily-increase-hd-free-space-lap top.html

How to free up my disk space

 Cheers, Tom 😉

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Feb 3, 2009 11:07 AM

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Feb 3, 2009 11:59 AM in response to Texas Mac Man In response to Texas Mac Man

I agree with TMM about not stating a percentage but an absolute value. Some people run OSX on 1000 GB drives and others on 10 GB drives (yes, a bit too small).

Another way to look at this is to see what you actually are using. Open Activity Monitor and check the amount of virtual memory (VM) that is being used. My computer regularly uses 6 GB. This is hard drive space that is being used. The empty space on a drive is often broken up and the less the space the longer the computer has to hunt for places to put temporary files and the slower things happen. I like to leave at least 3x the VM space free on my drive. The 3x doesn't come from any place in particular, but I feel it is leaving enough wriggle room for OSX to find places for files easily.

Feb 3, 2009 11:59 AM

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Question: How much hard drive space to leave free?