SSD Reconditioning Tip (Run Disk Utility from Boot CD)

Discussion in 'MacBook Pro' started by BigshotMD, Jan 31, 2011.

  1. BigshotMD macrumors newbie

    Sep 1, 2009
    SSDs as you all may know are blazingly fast. However, I've had some hiccups with them being a newbie to it, upgrading from my WD 5400 Scorpio.

    So here's my experience with SSDs so far, which I'd like some explaining if someone can draw some sense:

    - I decided to free space erase whilst running Mac OS X Snow Leopard (10.6.6) on my boot drive. BAD IDEA. That made my SSD almost 10X slower for some reason. Start up times doubled, with the shut down times 10X slower.

    - Then I read somewhere to free space erase booting off either a the Snow Leopard DVD or from another drive. Decided to boot of snow leopard install. Ran free space erase again, then verified the disk. Restarted. Back to the previous start up times.

    It's odd that free space erase works when booting from another drive/DVD, but it worsens the performance if it is run from the SSD. Can anyone explain this?

    I have not tried disktester to recondition as suggested by some users from the article here:

    If someone can verify that booting from snow leopard DVD reconditions the drive, then it's a free and easy way to do it.

    Great to have some input.
  2. Muscle Master macrumors 6502a

    Muscle Master

    Oct 15, 2010
    hmm.. I would just use GParted to secure erase your data, these drives are too expensive to experiment on

    When you erase your drive via dvd.. did your performance return or decrease, or remained the same after the 1st time you erased ? And what SSD are you using?
  3. Eddyisgreat macrumors 601

    Oct 24, 2007
    It doesn't, simple as that. I respect diglloyd, but I think his article is misleading and talks about other aspects of SSDs and not necessarily performance loss due to write-rewrite cycle that i'd expect.

    Nutshell: Disk utility writes 0s (or random pattern depending on method) to the drive. This isn't what you want for an SSD; it's what you want for traditional HD storage.
    For an SSD, you want the cells EMPTY. not 1's, not 0's, completely empty. Before a controller can write over a 'dirty' (not empty) cell, it needs to be erased. This cycle introduces some delay.
    To erase the cells as empty, you need a file system that supports TRIM (which isn't OS X ;) ) OR a way to issue the ATA SECURE ERASE command. This isn't available from OS X.
    You'll need to boot into another solution like this. It's what I, and many others have used with lots of success.
    Once you issue the ATA SECURE ERASE command, all the cells will be blanked out, and your SSD will be back to 'factory' speeds since it doesn't need to do the erase-rewrite cycle.
  4. jenzjen macrumors 68000

    Aug 20, 2010
    This is probably better merged into this long thread *if* it really works:

    I don't see how it does work, but I can't argue with hard facts. OP, can you do this?

    1. Run a real benchmark right now that's dependable (lots of benchmarks are horrible for SSDs, I don't know which one to recommend) or just transfer a huge huge amount of data timing the results. Are these results the same as factory fresh?

    2. Do the erase thing that slowed down the drive and run the test again.

    3. Do the erase thing via the boot CD and run the test again. Are you back to #1 speeds?
  5. Eddyisgreat macrumors 601

    Oct 24, 2007
    It does.
  6. BigshotMD thread starter macrumors newbie

    Sep 1, 2009
    I haven't run benchmarks, but I can easily confirm the boot time and shut down time. When I first installed Mac OS X Snow Leopard 10.6.6 with all my apps on the new SSD (Corsair F-120 GB), it took 28 seconds to boot (my Macbook is over two years old, late October 2008 model).

    Stupidly ran secure erase from Disk utility booting from SSD. Boot time was 1 min 10 seconds. Shut down time is 23 seconds.

    Ran disk utility from boot DVD (snow leopard install DVD). Every back to original state.

    Can't really explain this.

    Yes, I am aware that writing 0s is not the same as making cells empty. BTW, does digilloyds do this?

  7. jenzjen macrumors 68000

    Aug 20, 2010
    Boot time can be affected by many things during the initial re-install. On my SSD, I see boot times sometimes triple for the 1-3 restarts until something in the system settles down. Another time, I had to do both a PRAM and SMC reset to get my boot times back after a clean install hence why I suggested benchmarks.

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