How much free space should I leave on my SSD?

Discussion in 'MacBook Pro' started by MathBunny123, Aug 20, 2013.

  1. MathBunny123 macrumors regular

    Joined:
    Oct 19, 2012
    Location:
    Toronto, Canada | Sibiu, Romania
    #1
    Hello! I currently have about 50GB of free space on my SSD, but I was thinking of leaving around 10GB left for Mac OS X...is that too little? I have a 256GB SSD...:confused:
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    As a general rule, it's a good idea to leave around 10% of your drive free, more if possible.
     
  3. MathBunny123 thread starter macrumors regular

    Joined:
    Oct 19, 2012
    Location:
    Toronto, Canada | Sibiu, Romania
    #3
    Thanks!
     
  4. paul-n macrumors regular

    Joined:
    Jul 12, 2012
    #4
    For maximum performance you should have at least 10% free or better up to 20%.
     
  5. SolutionsEtc macrumors newbie

    Joined:
    Aug 20, 2013
    #5
    The ol' 10% rule doesn't really apply to today's larger drives. There are 2 things to consider with ssd drives: virtual memory and garbage collection.

    Check your page outs in the memory pane of activity monitor. If the number is big, you need to install more ram as you're running low on memory and this is causing a lot of unnecessary writes to your drive.

    Ssd drives depend on garbage collection routines (trim, etc.) to erase the flash memory in unused blocks. This happens at idle. If enough free blocks are not erased, it will dramatically slow down write times.

    So it really depends on your work flow as to how much free space is enough. If you're regularly working with large files like video, 10GB is probably not enough. If your usage is simple documents like word processing files and spreadsheets, 10GB will be plenty to support these and the various system overhead such as cache files.

    HTH
     
  6. AXs macrumors 6502a

    AXs

    Joined:
    Sep 7, 2009
    #6
    I don't understand this "leave 10%" rule of thumb. Has it been factually proven with the SSD? Specifically the PCIe SSD in 2013 Airs? Or is it just a myth that has grown to legend?
     
  7. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #7
    The 10% is not a hard and fast rule, but rather a general estimate. Performance can be reduced if a drive is too full, as there needs to be free space for growing logs, caches, user files, paging, etc. Obviously, if the drive is larger, such as 1TB, the percentage can be somewhat smaller. The point is, it's not a good idea to fill up the drive.
     

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