10.6.8 TRIM Question

Discussion in 'MacBook Air' started by jfyrfytr25, Jun 27, 2011.

  1. jfyrfytr25 macrumors 6502a


    Dec 6, 2008
    I am not an expert on SSD's but I Familiar to know what TRIM is and what it does. what I can not find is if the performance degradation that a drive may experience by not having TRIM in the OS is permanent or if it can be reversed.

    Subsequently I would like to know if my October 2010 MBA 11.6" that has been running for 9 months with no TRIM will be repaired (if needed) by now having the TRIM supported.

    anyone know?????
  2. amarcus macrumors 6502

    Feb 26, 2008
    London, UK
    Yes, the performance degradation can be reversed. However you must use disk utility or some other software to "erase free space" thereby issuing the TRIM command to the SSD.

    Enabling TRIM will not improve performance (but will prevent further performance loss) unless you take the steps mentioned above. However if you haven't noticed any drop in performance then I wouldn't bother.

  3. zub3qin macrumors 65816


    Apr 10, 2007
    Prior posts (prior to 10.6.8) suggest that to speed up boot times which for some reason slow down with TRIM enabled, one needs to issue some sudo commands.

    Is this still necessary since we are not using TRIM enabler, but rather something built into the OS activating our TRIM? I hate issuing those sudo commands since I have no idea what the effect really is!
  4. adcx64 macrumors 65816


    Nov 17, 2008
    Slowdowns due to lack of TRIM is reversible. A good way to fix it is reformatting, but if you can't do that, take the advise of the posters above. ^^^^
  5. Susurs macrumors 6502a


    Jun 18, 2010
    Is boot time the same on 10.6.8 as on previous versions on Air..around ~14 seconds with TRIM now enabled?
  6. axu539 macrumors 6502a

    Dec 31, 2010
    Using disk utility to erase free space will not only NOT help with any performance degradation, but it will cause more, because the erase free space command is the exact opposite of the secure erase command that SSDs need to be wiped. If you want to actually wipe and restore an SSD to stock condition, you'll need to issue the secure erase command from a linux environment, which involves a lot of hoops to jump through.
  7. dabear macrumors newbie

    Mar 4, 2011
    I would like to see some sources backing up your claim. I am on a macbook 3,1 with an intel 80 gen2 ssd. I tested performance multiple times before and after doing an erase free space from disk utility(using drive tests from xbench). performance was way higher after.
  8. Bigmacduck macrumors regular

    Feb 15, 2009
    You can force TRIM by booting into single user mode command prompt and run fsck with the right options. Your SSD must show up as TRIM support YES. if not use TRIM Enabler.

    Here is how to:

    1. Switch on your MacBook
    2. Hold COMMAND and S key simultaneously
    3. Once you arrive at the command prompt type: fsck -ffy
    4. During the last step of fsck you will recognize a message that says "trimming unused blocks". Depending on the state of you SSD that takes anywhere from a few seconds up to a minute or so.
  9. ZipZap macrumors 603

    Dec 14, 2007
    For those not familier with these command....what the heck does this do: fsck -ffy
  10. pil0tflame macrumors member

    Apr 19, 2011
    London, Ontario
    fsck = File System Check

    -ffy = scan file system and fix problems specific to an SSD drive (-fy is the non-SSD option)

    I'm not 100% on the -ffy option vs -fy, but a quick search confirms this command causes a TRIM operation on an SSD.
  11. amarcus macrumors 6502

    Feb 26, 2008
    London, UK
    I'm afraid it's probably best to still issue those commands. For those of you that are unaware, after performing "erase free space" in disk utility you are advised to enter the following commands in terminal:

    sudo chown root:admin /
    sudo kextcache -system-prelinked-kernel
    sudo kextcache -system-caches
    The above commands rebuild the caches used by OS X (mainly during boot) that identify the locations of essential files. The "erase free space" operation tries to make the free space contiguous to facilitate in writing over it - you can think of it a bit like a defrag of the free space on your drive. A potential side effect of this is that some of the essential OS files might be relocated. Therefore unless the caches are rebuilt they can now be pointing to invalid file locations. Ultimately this can contribute towards a significantly slow down system boot.

    What are you talking about? I think your confused with when TRIM is not enabled.

  12. jfyrfytr25 thread starter macrumors 6502a


    Dec 6, 2008
    Thanks everyone. Following the steps you guys said I have sgnificantly increased the speed of my SSD. when I bought it I could boot within 12-13 secs. lately it had gotten to be about 18-20.

    Now I am back to to about 13 sec boots.

    Again thanks.

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