Macbook Air 2011 + USB Drive

Discussion in 'MacBook Air' started by BigMcGuire, Aug 15, 2012.

  1. BigMcGuire macrumors demi-god

    BigMcGuire

    Joined:
    Jan 10, 2012
    Location:
    California
    #1
    Quick question. I just recently noticed I could drag/drop applications I'm installing to my USB external hard drive (320GB wd passport). Since my Macbook Air is on all day I figured I'd save the SSD some writes and install Firefox to the USB Drive. So I drag/dropped the Firefox installation icon to the USB drive and it seemed to work.

    Seems too good to be true, is everything being stored on the USB drive? Can I do this with other applications that don't have to run all the time?

    Thanks,
    -Paul
     
  2. mmomega macrumors demi-god

    mmomega

    Joined:
    Dec 30, 2009
    Location:
    DFW, TX
    #2
    You can move your entire applications folder, documents and downloads to the external if you want.:D
     
  3. BigMcGuire, Aug 15, 2012
    Last edited: Aug 15, 2012

    BigMcGuire thread starter macrumors demi-god

    BigMcGuire

    Joined:
    Jan 10, 2012
    Location:
    California
    #3
    Looks like I spoke too soon. Firefox, even though installed the USB drive still stores the cache in the User/myname/Library/Application Support/Firefox folder.'

    lol @ moving entire applications folder. Yeah, I'm not that paranoid yet. I tried PortableApps on a USB drive till it got so hot it smelled like burning plastic and my Mac said it was using too much power and disconnected it. lol
     
  4. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #4
    Normally modern SSDs have a theoretical write/read limit of 10,000 to 100,000 cycles (P/E cycles), meaning if you had a 64 GB SSD and its cycle limit would be 10,000, you would have to write 625 TB to it, which would be 351 GB per day everyday for the next five years. Assuming those numbers vary and it would only be a tenth of that, it would still mean 35 GB per day, which under normal usage no average computer consumer does, not even with temporary files.

    In other words, it is not necessary to do what you want to do just to save some write/read cycles (typically one cycle takes more than one day on a 64 GB SSD, even more than a week on bigger ones, unless you constantly write to it, in which case, moving Firefox or other applications onto an external HDD will not help anyway).
    SSD endurance

    PS: Normally applications use the Macintosh HD / Users / YOU / Library / Application Support / folder to write and read temporary files, thus it would make less sense to start applications from an external HDD (Firefox 11 is 80 MB in size, you would have to start it 52,428,800,000 times to fulfill 10,000 cycles on a 64 GB SSD - that is more than 52 billion times, 332 times per second over five years, SSDs can't even read that fast).

    ----------

    Sorry, it took so long for the reply to explain everything (had to do some research on numbers and do the the calculations), but you don't need to do that. Doing that would defeat the purpose of the SSD and limit you to USB 2.0 speeds and slow seek times. Isn't the SSD one of the positive things about the MacBook Air?

    ----------

    Now I am confused: SSD Life Remaining, am I understanding you wrong?
     
  5. BigMcGuire thread starter macrumors demi-god

    BigMcGuire

    Joined:
    Jan 10, 2012
    Location:
    California
    #5
    @ simsaladimbamba - you're right. I've done research too on SSD life - and it's insane. Some dude got 90 million on one test. Thanks for knocking some sense into me. Being tethered to a USB cable isn't why I bought the Macbook Air either.

    Thanks :p

    ------------------------

    No you got me right - I know that SSDs have a life remaining and it's longer than most of us will ever use our computers, probably for our lives, but you know ... the nerd in me is looking to keep wear and tear at a minimal, and running Firefox off a USB drive was a cool thought :p.

    Thanks for your post :)
     

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