Reconditioning SSD for clean OS install?

Discussion in 'Mac mini' started by ibizan, Jan 22, 2013.

  1. ibizan macrumors newbie

    Nov 1, 2012
    Apologies if this is the wrong place for this question (a search yielded no results).

    If I have a used (but fairly new) SSD ready to be wiped and freshly installed with the latest version of OS X, what's the best way to go about wiping the drive to get it back to its "factory-original" condition? Specifically, which options under Disk Utilty are viable? Security of the old data is a non-issue.

    I've read conflicting advice online; my understanding is that it's NOT a good idea to do a "secure erase" that zeroes out the drive.

    EDIT: I don't have access to a PC and the SSD's software tools are all PC-based. So there's that.
  2. Adz76 macrumors member

    Mar 3, 2011
    Dagobah System
    TBH I would have suggested the option that you have dismissed, but if that is out and security isn't an issue then I'd just go for a clean re install.

    I'm assuming its in a Mac the drive? If its not then using a usb caddy is how I'd do it, other wise I'd make a bootable usb stick first of your OS, there are guides somewhere on here and the web.

    Then I'd just do a clean install and you're set.
  3. mslide macrumors 6502a

    Sep 17, 2007
    Then you don't need to do a secure erase. Just reinstall OSX.

    It is if the drive had sensitive data on it and you are planning on giving/selling the drive to someone else. The fact that it's an SSD doesn't change that. It's not like doing one secure erase is going to instantly render the drive broken. These things are designed to last a long time.
  4. jav6454 macrumors P6


    Nov 14, 2007
    1 Geostationary Tower Plaza
    Disk utility can help you with anything you might need. You can zero out the drive if you want just recover the performance loss after usage.
  5. ibizan thread starter macrumors newbie

    Nov 1, 2012
    Sounds easy enough—still learning my way around SSDs and to what degree these solid state drives get fragmented over time. Could've sworn I read something about how zeroing data was a bad idea if TRIM wasn't properly enabled on the system (i.e., garbage collection routines alone weren't enough to bring the drives back up to factory freshness, as it were).

    Anyhow, thanks, all. I'll go with the quick + simple install.
  6. jav6454 macrumors P6


    Nov 14, 2007
    1 Geostationary Tower Plaza
    What is truly a bad idea is defraging an SSD. Big no-no.
  7. Mike Valmike macrumors 6502a

    Feb 27, 2012
    Chandler, Arizona
    Yes but I believe the OP's concern is the write cycles for an SSD which zeroing out the data would consume a significant number of. Honestly this is an issue I have not yet had to encounter so I am curious to know what the best answer is.
  8. ibizan thread starter macrumors newbie

    Nov 1, 2012
    Exactly! SSDs haven't been around long enough; every article I read about long-term stability ends up being conjecture. Can't find a concrete "This is the proper way SSDs should be handled and reformatted" guide anywhere at the moment.
  9. hfg macrumors 68040


    Dec 1, 2006
    Cedar Rapids, IA. USA
    From posts by those more experienced with SSDs here, I have concluded that SSDs slow down as all the cells are written-to (programmed), whether by data, all '1', or all '0', and they must be "reset" to a non-programmed state to regain their speed. This is normally done with the controller "garbage collection" and/or by the OS with "trim". Otherwise, when data is written to a programmed location, that block must first be reset, then written, causing the slower performance. Thus, performing a "secure erase" whereby all ''0' data is written to the entire array without allowing idle time for the cleanup, is actually the worst thing that can be done to a SSD.

    I have seen no "quick initialize" methods in OS X to reset a SSD back to its virgin out-of-box state. However, I have seen discussions on how that can be done if you can put the SSD in a Linux or Windows environment and run base-level commands.

    I would like to see a method for doing this SSD reset within OS X if anyone knows how. :)
  10. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Okay... here's the deal. SSDs use NAND chips to store data, and those chips have individual cells on them that will begin to degrade after a given number of write cycles. Some of the newer SSDs use a type of NAND called TLC NAND, and it can handle ~1,000 life cycles. Give this article a read.

    So let's say you have a TLC NAND SSD. If you look in the article you will see a chart that shows it would begin to degrade in 11.7 years IF you wrote 10GB to the drive EVERY SINGLE DAY, which for most of us is not going to happen.

    So back to your question. When you do a secure erase with a one pass of zeros, you have just "used up" one of the 1,000 write cycles of every NAND cell on the drive. As a practical matter (doing the math off 11.7 years) this means the SSD will begin to degrade in 4,265 days instead of 4,270 days.

    Remember, this is with the TLC NAND at 1,000 life cycles. MLC NAND has 3,000 life cycles, making this even less an issue.

    Short version. I would not run secure erase every week, but it will not matter much if you do it occasionally.

    IMO everybody is a little too concerned about this issue with SSDs.

    Back to your first post though. If you are not concerned about data recovery, there is no reason for you to secure erase. Just format the drive normally to Mac OS Extended and use it.


    You are correct that a Disk Util secure erase with zeroes, would put the drive in a state where write speed is slowed due to the state of the cells, but if left to idle for a time after that the built in garbage collection of the drive will restore this to like new performance. If you look at some of the Anandtech SSD reviews they have a great chart in the TRIM performance section that shows drive speed recovery both with and without TRIM. They all recovery either way, although they recover faster with TRIM.

    Another way to instantly restore like new performance in OS X is to install the TRIM hack then boot to single user mode and enter the command "fsck -fy". This will TRIM all unused blocks on the drive.

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