External SSD - long term use

Discussion in 'iMac' started by ivanwi11iams, May 19, 2016.

  1. ivanwi11iams Contributor

    ivanwi11iams

    Joined:
    Nov 30, 2014
    Location:
    Atlanta, GA
    #1
    For those using an external SSD, to run the OS, have you noticed any long term issues?
     
  2. Willo34 macrumors regular

    Willo34

    Joined:
    Feb 5, 2015
    Location:
    Netherlands
    #2
    I havent, must say. Is working well here.
     
  3. panzer06 macrumors 68030

    panzer06

    Joined:
    Sep 23, 2006
    Location:
    Kilrath
    #3
    Me either. No issues. Using same drive for the last 3 years. May upgrade next year and move this one to backup.
     
  4. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #4
    I've been booting and running my late-2012 Mac Mini using a Crucial SSD mounted in a plugable.com "lay-flat" USB3/SATA dock for more than two years now.

    Still runs as good as the first day I set it up.

    And -- something I consider quite significant in the discussions as to whether "TRIM" really counts for much with SSDs -- it's never had TRIM enabled (impossible with USB) and still runs as fast as when it was new.
     
  5. wlossw macrumors 6502a

    wlossw

    Joined:
    May 9, 2012
    Location:
    Montreal, Quebec, Canada
    #5
    If the drive has a significant amount of free space, or plenty of time to run it's own garbage collection you probably wont notice a difference...
     
  6. ivanwi11iams thread starter Contributor

    ivanwi11iams

    Joined:
    Nov 30, 2014
    Location:
    Atlanta, GA
  7. h9826790, May 20, 2016
    Last edited: May 20, 2016

    h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #7
    Depends, if the external connection type is USB but not TB, the "free space" have to be "free from the OS", that means those free space is never included in any partition after a "secure erase". Otherwise, since USB connection do not support TRIM, GC cannot use those "free space"(in the file system's point of view, they are free) and eventually the whole SSD will be "full" (in the controller's point of view, they are not free).

    Therefore, after a long period of time, the SSD's writing performance may be reduced, because the controller has to do a lot of work when writing, but can't prepare the free cell in advance (by GC) during idle.

    To alleviate this problem, either choose a SSD that has large over provision. Or create the over provision on your own. Which means "secure" erase the SSD, and then only create a partition that about 80% of the SSD's total capacity, leave the remaining 20% never touch (and cannot touch by the OS file system). In this case, the SSD controller now can confirm these 20% are free space (without TRIM), keep using them for GC, and prepare the free cell for future writing action.

    The downside very obvious is that you loss 20% space straight away, however, since you should keep some free space on a SSD anyway, and you can actually use up to 100% on your partitioned space. Therefore, eventually, still more or less the same as partition 100% capacity with TRIM enabled but manually keep 20% free.
     
  8. cat40 macrumors newbie

    Joined:
    Jan 30, 2010
    #8
    what setup doe you use?
    --- Post Merged, Nov 17, 2016 ---
    and have never had a freeze / hang?
     
  9. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #9
    I have a Samsung T3 that's been running for the last couple of months, nothing long term yet but its been solid so far.
     
  10. IngerMan macrumors 6502a

    IngerMan

    Joined:
    Feb 21, 2011
    Location:
    Michigan
    #10

    I know how to create a partition, for example I just secure erased a 275GB Crucial SSD. I then can add a partition of 55GB, but is there something special in formatting the 55GB. I don't understand the cannot touch by OS file system.
     
  11. ivanwi11iams thread starter Contributor

    ivanwi11iams

    Joined:
    Nov 30, 2014
    Location:
    Atlanta, GA
    #11
    I'm guessing it was formatted for OS, versus FAT32 or NTFS, right?

     
  12. IngerMan, Nov 18, 2016
    Last edited: Nov 18, 2016

    IngerMan macrumors 6502a

    IngerMan

    Joined:
    Feb 21, 2011
    Location:
    Michigan
    #12
    Yes Extended Journaled, But my question is if you create the 2nd partition after secure erase do you then eject it or do you keep it mounted and just don't use it?
     
  13. bent christian Suspended

    bent christian

    Joined:
    Nov 5, 2015
    #13
    You need to erase that partition. It is done through Terminal. I don't have the code in front of me and can't seem to find it immediately online. I can post later unless someone else has it handy.

    EDIT: I think this is it:

    https://forums.developer.apple.com/thread/18776
     
  14. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #14
    cat40 wrote:
    "and have never had a freeze / hang?"

    Nope.
    No sleep problems, either.

    I should mention that in experimenting with El Capitan, I was getting hangs and kernel panics at shutdown. After a long time of being frustrated with it, I discovered that the reason was because I had manually turned off memory compression during my setup. I turned it back on and the hangs/kp's disappeared...
     
  15. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #15
    NO, leave that 55GB NEVER partitioned (after secure erase). Because once partitioned, data may be written on it. And they are now managed by the file system. Without TRIM, the controller can't tell which cell's data can be destroyed and free it up for GC.

    The whole idea is to leave that 20% space always free for the controller. And never belongs to any file system. So, the controller know it can be used that for GC without helping from TRIM. Technically, we just manually create a 20% over provision for GC to work properly without TRIM.
     
  16. IngerMan macrumors 6502a

    IngerMan

    Joined:
    Feb 21, 2011
    Location:
    Michigan
    #16

    Thank you Bent Christian, I read it but I am not confident enough to do anything with it. I deleted the one partition, I guess Ill just make sure not to use over 220GB of my 275GB on my external USB SSD and see how it goes.
     

Share This Page