TRIM and Garbage Collection (GC) are not the same, and are both necessary to maintain performance after the drive has been used for a while. GC only takes place in the background when idle, or when the OS needs to write to a previously used block.
TRIM proactively zeros unused areas in the background. This is why you see a slight performance hit, but on an SSD this is negligible and is a lot faster than waiting for GC to work on demand after you've been using the SSD for a while.
Using the TRIM enabler app is not advised, but you can enable it via the terminal by following these steps.
Including the Steps below (as there seems to be a certificate issue with that particular link) :
TRIM Enabler for OS X Lion, Mountain Lion, Mavericks
OK. Now that Lion’s out, people want their SSD TRIM support back. I
have one thing to say:
DO NOT USE TRIM ENABLER (VERSION 1.1 OR 1.2) TO ENABLE TRIM ON LION.
After a little inspection of this application, I found that instead of
patching the file, it replaces an entire kernel extension. This means
that when you use TRIM Enabler with Lion, it replaces a critical
kernel extension, with lots of dependencies, with an older one (from
Snow Leopard 10.6.8). This is bad. Very bad. While TRIM does become
enabled, the kernel extension you now have has the potential to cause
a ton of problems. That means anything from kernel panics, to disk I/O
delays…and the dreaded spinning beach ball.
After confronting the developer, Oskar Groth (who I refuse to link
to), via his blog’s commenting system, I was told that I was simply
trolling and spreading fear (even though I offered the alternative I
share here). Apparently, the next version of TRIM Enabler will
correctly patch the file, instead of replacing it, but that hasn’t
happened yet.
So, here’s the proper way to enable TRIM support. Run these commands
in Terminal:
- Backup the file we’re patching
sudo cp
/System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage
/System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage.original
- If you’re using OS X Yosemite, disable KEXT signing
sudo nvram boot-args="kext-dev-mode=1"
- Patch the file to enable TRIM support
FOR ML 10.8.5 AND MAVERICKS DP4+
sudo perl -pi -e
's|(\x52\x6F\x74\x61\x74\x69\x6F\x6E\x61\x6C\x00{1,20})[^\x00]{9}(\x00{1,20}\x54)|$1\x00\x00\x00\x00\x00\x00\x00\x00\x00$2|sg'
/System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage
- Force a refresh of the system’s kernel extension cache
sudo touch /System/Library/Extensions/
- Now Reboot!
a) If in the future you want to disable TRIM support
FOR ML 10.8.5 AND MAVERICKS DP4+
sudo perl -pi -e
's|(\x52\x6F\x74\x61\x74\x69\x6F\x6E\x61\x6C\x00).{9}(\x00\x54)|$1\x41\x50\x50\x4C\x45\x20\x53\x53\x44$2|sg'
/System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage
sudo touch /System/Library/Extensions/
b) If something goes horribly wrong, restore the backup
sudo cp
/System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage.original
/System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage
All this patch does is simply replace the string “APPLE SSD” in the
file IOAHCIBlockStorage with zeros. This happens to bypass the
restriction of only allowing Apple branded SSDs. The backup of the
original file is saved in the same directory as the original file.
To check if it worked, open up About This Mac, click the “More Info…”
button then the “System Report” button. In the list on the left,
choose “Serial-ATA”. Click on your SSD Drive and in the lower half of
the screen you should now see “TRIM Support: Yes” instead of “No”.
Remember, if you have an older generation SSD, the hardware itself may
not support TRIM …and therefore this patch won’t help you. This patch
bypasses the restriction put in place by Apple to restrict TRIM
support to Apple branded SSD drives.
You WILL need to re-apply this patch after each major update of OS X.
That means for 10.7.1, 10.7.2, etc.
Credit where credits due, unlike the other TRIM Enabler, I originally
found this on the InsanelyMac forums by digital_dreamer
As a note, the MD5 checksums for the original and patched file on
10.7.0 are as follows:
Original: 155b426c856c854e54936339fbc88d72
Modified: 945944136009c9228fffb513ab5bf734
If you have already used the other TRIM Enabler, you can do the
following: a) Attempt to copy and replace the extension from another
Mac running the same version. b) Attempt to copy and replace the
extension from the Recovery partition (Open up Disk Utility and Mount
Recovery HD) c) Reinstall Lion d) Wait it out till 10.7.1 and hope
that the extension is replaced in the update (but it may not be), then
re-patch the file
UPDATE
a) Applying this patch does NOTHING else other than enable TRIM for
3rd party SSD drives. If you start seeing other problems, they’re not
because of this.
b) Using this patch has no effect on hard disk drives. Firstly,
mechanical hard disk drives do not understand the TRIM command, so it
is discarded. Secondly, the Apple driver isn’t stupid enough to send
TRIM commands to your hard disk. It knows the difference between an
SSD and a HDD.
c) The wiping free space option is ALWAYS greyed out, even on Apple
based SSDs. As reported here, you can try using fsck -ffy in Single
User Mode, but personally I haven’t tested it. I’m sure there isn’t
too much to worry about, especially if your drive has garbage
collection.
d) If TRIM isn’t enabled after patching either a) you didn’t follow
the steps correctly or b) your drive doesn’t support TRIM. If your
drive doesn’t support TRIM, there’s no need to revert the patch, it
simply has no effect.
e) The TRIM patch is NOT vendor/model specific. You can patch the
driver for any damn SSD drive. Hell, you can apply the patch if you
only use HDDs, but that’d be a little silly.
f) Regarding RAID and SSDs on Mac. I’m not completely sure but…if
you’re using Apple RAID then I assume TRIM will work as usual. If
you’re using a hackintosh and using a RAID controller (i.e. Intel
ICHR), then no, RAID will not work. In either case, you should use a
drive with garbage collection.
UPDATE 2
Regarding SSD durability and comments by Hyram:
The durability of SSDs has sweet fuck all to do with Mac OS X TRIM.
It’s a fact, and always has been, that SSDs aren’t as durable as hard
disks. This is simply due it it being a new technology. SSDs fail
often due to the wear on the cells incurred by reads and writes.
If you don’t know what TRIM is, you probably shouldn’t be using a 3rd
party SSD drive. Many have reported these commands don’t work, but
that simply isn’t true. It just shows that a lot of people here don’t
know how to use Terminal, don’t know what Bash is, nor Perl. These
aren’t the sort of people that should be messing around with this.
Instead, buy a SSD drive that offers garbage collection….or a Mac with
an Apple SSD.
There has also been some confusion about garbage collection and TRIM.
TRIM is ALWAYS preferred over Garbage Collection and will likely yield
better results. If you have garbage collection, you don’t necessarily
need TRIM, but it’ll probably offer better performance and there’s
always a chance there’ll be a degradation of speed over time.
Therefore, when using Garbage Collection, you may have to take the
drive out and do a secure erase so that everything is re-marked as
free space.
A drive will never fail because you haven’t enabled TRIM, even if it
doesn’t have garbage collection. They simply become slower and the
speed is not restored until you perform a destructive erase on the
drive. However, drives that support TRIM, but do not have GC, and do
not have TRIM enabled (in the OS) may fail more quickly than without
enabling TRIM. In a very basic sense, since the SSD is no longer told
what data to free up, when writing new data it will also re-write the
deleted data, essentially causing more write cycles and wearing down
the durability of the drive. If TRIM were enabled, the new data would
be written without the deleted data, and hence less write cycles and
extended durability. This ONLY relates to the combination of a drive
that supports TRIM with no GC, while TRIM is disabled in the OS
Running garbage collection and TRIM at the same time is NOT a problem.
They’re designed to work together. You can look at it like so: TRIM is
called by your OS each time space is freed up. Garbage Collection is
run by the drive’s firmware when idle and determines which parts of
the drive can be cleaned up and rearranged. TRIM is obviously more
efficient and obviously the drive’s firmware is aware of the TRIM
commands and accounts for this.
As for the statements by Hyram, I believe some of them to be
completely false. While it’s true that using TRIM and garbage
collection at the same time is essentially using two mechanisms to do
the same thing, the firmware on your SSD drive is designed to handle
these things. All SSD manufacturers, GC or not, recommend the use of
TRIM.
There is zero evidence that Apple has specific code to handle their
specific SSD hardware for reading and writing. TRIM is a standardized
ATA command. However, it IS likely that Apple has designed their
integrated SSDs (particularly in the Air) to not overheat. Basically,
your SSD is likely to fail just as much in your MacBook as if it were
surrounded by the same temperature in any other laptop.
Posted on November 17, 2011
Best Answer
a. Trim is not really necessary on modern SSD's. GarbageCollection works pefectly fast when there is enough free space, say 20% or more. b. Do not use Trim when the SSD has not a modern Marvel controller (never install trim on a SSD with Sandforce controller. The new Sandisk SSDs have a Marvel controller, I do not know what controller is in the Sandisk Plus.