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I am trying to downsize my iMac 640Gb disk to make it fit onto a 120Gb (113Gb usable) SSD. The total size of use files is currently approximately 340Gb, of which my home folder accounts for 265Gb (which I intend to not put on the SSD, or at least not all of it). Very rough calculations suggest that my OS and application files are taking up roughly 75Gb, which puts me approximately 2/3rds full - not bad.

But, I would like to reduce this a little further if possible, to ensure that as and when I continue to use the computer (and I have a number of large apps that do not currently have installed including music production apps with a lot of data) I am not worried about running out of space on the boot drive.

To this end I already own XSlimmer which I will use periodically to remove PowerPC and language variants from my apps, but I was wondering if there are any areas of the Base OS that I can safely remove to save further space? I am thinking about things like OS localisation, the location of the included screensavers and wallpapers, the voice files that are used for text-to-speech etc.

Is there a significant amount of such data that can be easily removed to save a few extra Gb on the boot disk?

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What version of OS X are you running? –  cksum Apr 17 '12 at 22:32
    
Tagged Lion, latest patches –  stuffe Apr 17 '12 at 22:51
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4 Answers

up vote 14 down vote accepted

We get a lot of questions about this topic here. You can search for earlier similar questions and answers.

Backup first

Make a full backup of everything, a complete disk image, before you go on a spree to delete resources from your Mac.

Deleting More Unused Human Language Resources

Monolingual, which is free, can delete unwanted language support files in the /System/Library/ and /Library/ folders itself, whereas XSlimmer (which I also use) is only set up to delete language support files in the Applications folder.

iPhoto

You can "thin out" iPhoto by removing its voluminous printing templates, but if you delete them, you won't be able to print anything from iPhoto at all.

Right-click on iPhoto in /Applications/iPhoto/ and select "Show Package Contents". You'll discover several hundreds of megabytes of files in /iPhoto/Contents/Resources/Themes/. You can actually delete these (authentication required) but it will change the behavior of the iPhoto app.

Speech synthesis voices

Removing system support files from the /System/Library/ folder is dangerous. The only files I know of that you can safely delete are the speech synthesis voices in /System/Library/Speech/Voices/. You should leave one voice in there should you ever need that feature.

Fonts

You can save several dozen megabytes by deleting certain Asian fonts if you don't need them. Don't delete system fonts directly in the Finder. Rather, do it through the Apple Font Book application, which will prevent you from deleting the "reserved" system fonts that Mac OS X expects to see when it boots up, but permit you to delete "non-essential" fonts.

Screen savers and desktop pictures

Screen savers are in /System/Library/Screen Savers/.

/Library/Desktop Pictures/ has a couple of hundreds of megabytes of files you don't need.

Dictionaries

Mac OS X has a Japanese dictionary and thesaurus, several hundred megabytes in size, in /Library/Dictionaries/. You can safely delete these if you will never need them.

GarageBand and iDVD files

If you do not use GarageBand or the older iLife program iDVD, you can save many tens of gigabytes by deleting their applications but especially their support files in the /Library/ directory.

With regard to GarageBand, depending on your installation, several gigabytes of data can be removed from two places:

/Library/Application Support/GarageBand/

/Library/Audio/Apple Loops/Apple/Apple Loops for GarageBand/

Printer drivers

Depending on your installation, you may have several gigabytes of printer drivers for printers that you have never actually used. If you are willing to take the trouble, you can delete everything in /Library/Printers/. The next time you turn on one of your printers and try to print to it, Mac OS X Lion will prompt you to download and install the driver needed for that printer alone.

Utilities to help you find files to delete

There are several utilities to list all the files on your hard drive and sort them by file size in various types of charts and graphs. These include: OmniDiskSweeper, which is free; WhatSize, a commercial app; and DaisyDisk. All these are useful not only for looking at system files but also for examining your Documents and user data. You'll find old files that you don't need and can archive or delete, saving further disk space.

Just remember

Just remember that if you do not know what you are doing, you might damage your system and then the only remedy would be to do a complete re-installation of your OS, which would put you right back where you started.

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Thanks Wheat, that's very useful - I can pretty much see everything you mention, although I am not 100% sure on the Dictionary and Fonts you mentioned. –  stuffe Apr 18 '12 at 9:04
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I have added additional instructions in my answer. –  Wheat Williams Apr 18 '12 at 12:53
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And I've added extra tips regarding printer drivers and utilities for cataloging and measuring disk contents. –  Wheat Williams Apr 18 '12 at 13:13
    
Comprehensive updates - thanks :) –  stuffe Apr 18 '12 at 13:56
    
@stuffe To get some real world numbers: How many GB did you save by just using these tips? –  gentmatt Jul 15 '12 at 12:20
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/var/vm/sleepimage can take up the same amount of disk space as the amount of RAM your Mac has depending on the safe sleep mode.

~/Library/Caches/com.apple.Safari/Webpage Previews/ is at most about 1GB. If you don't need Top Sites or the cover flow views, you can tell Safari to not save the thumbnails with defaults write com.apple.Safari DebugSnapshotsUpdatePolicy -int 2.

/private/var/folders/ might contain cache folders for applications that have already been removed or partially downloaded documentation files. You can sort the folders by size with du -sm /private/var/folders/*/*/*/*/ | sort -rn.

The installers for audio plugins often copy VST versions to /Library/Audio/Plug-Ins/VST/ or DPM versions to /Library/Application Support/Digidesign/.

If you've installed Xcode just to use Homebrew or some shell utilities, you might remove it and install the Command Line Tools for Xcode package instead.

The CJK fonts in /Library/Fonts/ take up about 500 MB of disk space. The System library already contains the most common Japanese and Chinese fonts.

~/Library/Autosave Information/ can contain old unsaved documents that haven't been deleted properly.

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Good additional suggestions! I forgot about Safari's Webpage previews. I have this disabled on my Mac also. –  Wheat Williams Apr 18 '12 at 21:37
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If you are going to use a SSD as main disk, you can set the hibernatemode to 0 and remove the sleepimagefile, which has the same size as your Ram. This has two advantages: no disk writing on the SSD, and no space lost on the SSD. Hibernatemode to 0 means that no image of the ram is being made onto the disk when you go into safe sleep. You do this with terminal commands: to see the actual hibernatemode: sudo pmset -g | grep hibernatemode this returns the actual hibernatemode you are in. to set the hibernate mode to 0: sudo pmset -a hibernatemode 0 and to remove the sleep image: sudo rm /var/vm/sleepimage That does it; when a serious update of the OS is made you check if the hibernatemode still is 0 with the above command. Note1: in some forums it is suggested to move the sleepimage file to another volume: DO NOT DO THAT: when the volume is not connected it will create crashes. Note2: if you add more Ram while you have hibernate mode not 0 this can create a startup problem because the sleep imagefile has the wrong size. To avoid that remove the sleepimage file before adding ram.

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Yes - you can clean things up to a point. I disagree with the characterization that Lion and Apps take upwards of 70 GB. Most of my installs of Lion end up under 15 GB before user data is added and that includes 8GB of /private/var/db/sleepimage to store RAM contents when the mac sleeps.

The apps take up 980 MB from Lion alone and even with all updates (10.7.3) and iLife installed from the App Store.

I really like WhatSize for measuring and slimming down existing drives safely by removing localizations (delocalize), un-necessary architectures (lipo suction) and development frameworks (nib'o suction). You will want the version from the web site to clean things since that is removed from the App Store version where needing admin permissions is verboten.

It also helps find duplicates of files and identify where your largest folders and files lie so you don't waste time cleaning up hundreds of small files to only save a few MB of disk space.

So - my space budget for a clean Lion install on a mac with 8 GB of RAM is:

  • 8 GB - sleep image
  • 1 GB - apps
  • 6 GB - all the rest of the system

What is getting you from 15 to 75 GB?

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"What is getting you from 15 to 75 GB?" Application support files consisting of a LOT of music sample libraries ;) –  stuffe Apr 18 '12 at 18:49
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Ouch - linking that entire folder to an external or spinning drive that doesn't go to sleep should be a nice workaround to spending serious $$$ on storing 60GB of loops on a larger drive. You could pick and choose amongst the apps, but I've never seen serious slowdowns moving the whole mess. –  bmike Apr 18 '12 at 18:58
    
Yes, move your virtual instrument sample libraries and loops to an external fast hard drive or SSD connected with Firewire, Thunderbolt or something else fast. This will also generally speed up the operations of your DAW (digital audio workstation) work. –  Wheat Williams Apr 18 '12 at 21:39
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