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I recently bought an SSD (a 64GB Crucial M4 - which I believe has garbage collection, based on these specs) for my new computer. I've installed OS X 10.7.2 on it, and would like to reinstall this and also install Windows 7 and Ubuntu on it. I'd like to know how to do so, for each OS, to best promote its longevity. This covers how/if to enable TRIM, and what/how to symlink to my hard drive.

In particular, I'm looking to clarify the following for OS X:

  1. OS X's built-in TRIM only supports Apple-approved SSDs, but you can enable it for others with these terminal commands or this app. There are some warnings that doing so will damage your SSD, but since my original edit of this question I've been convinced (here) that it's safe - still, it'd be good if someone could confirm this.
  2. I've symlinked most directories that are large or will be written to frequently. However, I'm not sure whether to do this for my Library directory; it seems like that'd cause a performance hit, but it's written to frequently by Quicksilver etc.
  3. I'd also like to move the swap directory to HD. An app called XSupport is meant to do this but I can't find it. There are unanswered SuperUser questions on how to do this at Moving Swapfile in Mac OS X Lion and Should I symlink my /private/var/vm dir to another volume in OS X Lion?
  4. I'd like to confirm that an erase can restore performance of a degraded SSD. Many sources say this, this most convincingly:

(Places I've looked, more in my 'answer' below:,,, comments at

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“It has been exceptionally rare to find a solid-state drive in a desktop-OS environment that has remained functional for more than a year, and that six to ten months seems to be the average irrespective of brand” My year-old OCZ SSD, in a Mac, must be exceptional then… or maybe that article is just FUD. – Richard Kettlewell Dec 3 '11 at 14:41
This source suggests OCZ drives don't need - and shouldn't use - TRIM, which may be related. PS: Despite the different drive, it'd be great if you could turn your success into a general answer to my question about how to safely set up OS X booting from an SSD (TRIM? Symlinks to an HD? etc) – tog22 Dec 3 '11 at 16:23
I didn't do anything special, i.e. I treated it the same as I would a "spinning rust" disk of the same capacity (so yes, symlinks, but due to space limitations). – Richard Kettlewell Dec 5 '11 at 14:06
(I reworded my question in light of new research - no longer quoting the comment at that Richard quotes – tog22 Dec 8 '11 at 21:41
My advice, which is not an answer at all, but just don't worry about it. Keep backups, check warranties on drives (some brands are better with this than others, I've had people get fresh drives from Seagate that were 8 years old and out of warranty when they failed), and when it dies just replace it. I really don't think the amount of effort you could put forth here will really be worth any difference in total life. – ioSamurai Feb 6 '13 at 20:55
up vote 2 down vote accepted

Since I haven't heard anything, I'll create and keep editing a list of what I find here, in scrappy, note-like fashion. However I'd still welcome a more expert answer!

Possibilities (yet to do)

What I've done

  • The following stops OS X writing file access times when files are accessed, easily reversible by deleting the file:

Terminal commands:

echo '<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" 
<plist version="1.0">
</plist>' | sudo tee /Library/LaunchDaemons/com.noatime.plist
sudo chown root:wheel /Library/LaunchDaemons/com.noatime.plist
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