How close is an SSD to being as useful as RAM?

Discussion in 'MacBook Pro' started by danpass, Aug 17, 2011.

  1. danpass macrumors 68020

    danpass

    Joined:
    Jun 27, 2009
    Location:
    Miami, FL
    #1
    I'm not certain how to relate the two, I was just thinking if the whole SSD concept is so fast then the whole page in/page out situation when RAM fills up could be mitigated by having a really fast drive, i.e.: an SSD drive.

    How close is a 7200rpm disk? 10% as fast as typical RAM? 25%

    An SSD? 50% as fast?

    Just wondering.
     
  2. superericla macrumors 6502

    Joined:
    Sep 27, 2010
    #2
    DDR3-1333 RAM can reach speeds of 10667 MB/s while the typical SATA 3 SSD can run at around 550 MB/S. So RAM is basically around 20+ times faster than a typical SSD.
     
  3. 2hvy4grvty macrumors 6502

    Joined:
    Jun 17, 2011
    #3
    SSDs won't replace RAM if that's what you're saying... same reason RAM won't replace CPU cache.
     
  4. jamisonbaines macrumors regular

    Joined:
    Dec 14, 2007
    Location:
    CA
    #4
    Specs aside i have a netbook with OSX and SSD along with 2 GB of RAM and I'll be deep into page outs and rarely ever notice any lag like you would experience with a HDD.

    RAM is cheap enough to jump on 8 GB but if you're choosing between 16 GB or an SSD get the SSD.
     
  5. jimmie32 macrumors member

    jimmie32

    Joined:
    Feb 11, 2011
    Location:
    Beijing, CN
    #5
    As pointed out by 2hvy4grvty, basically,
    L1 Cache > L2 Cache > L3 Cache (Now called Last Level Cache, LLC, by Intel) > RAM (In general here) > SSD > HDD. Of course, you can't get more cache since its built into the processor, but if you are wanting to speed up your computer, changing to a SSD might yield more noticeable day-to-day performance than upgrading RAM.

    This is because, if you get more RAM, you'll only notice it in cases where you have many windows open / heavy multitasking. Sure, I do virtual machining, so 8GB is certainly noticeable once I get my Windows 7 VM open, but if you're just doing some basic work, not a big chunk of difference.

    A SSD is different though. It will make opening apps, saving things, reading things, much faster than a normal hard drive.

    Swap files on SSDs won't replace RAM anytime soon. SSD read/write speeds peak out at ~500MB/s, while RAM could hit ~10GB/s. SSD speeds might go higher, but well, RAM will go higher, too. We won't see a merge anytime soon. :D

    Perhaps we'll see RAM and SSDs merge when Mac and Windows merges. /s
     

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