What will happen if copy from SSD to HDD?

Discussion in 'Buying Tips and Advice' started by Ulf1103, Aug 4, 2011.

  1. Ulf1103 macrumors 6502

    Jan 5, 2011
    Hy, I've got a question.

    What will happen if someone tries to copy somthing from a new MBP with SSD to a new MBP with a 5400 RPM HDD using thunderbolt.
    I mean I have an HDD of 5400 RPM, so the max right speed should be around 86MB/s, but the ssd's is around 182MB/s.

    Will the ssd match the hhd right speed, or will the ssd copy it to the RAM of the other MBP?

    Ps: OSX Lion does support trim for it's own ssd's right?
  2. wywern209 macrumors 65832


    Sep 7, 2008
    do you rly want to know?
    nothing bad will happen. stuff will simply transfer at the lowest common denominator which in this case is the hdd
  3. Ulf1103 thread starter macrumors 6502

    Jan 5, 2011
    so, there will be no caching involved?
  4. gekko macrumors 6502

    Mar 20, 2009
    My best guess is, yes, but only a small fixed size copy buffer determined by the copy implementation or file transfer protocol in use.

    Why do you ask?
  5. Ulf1103 thread starter macrumors 6502

    Jan 5, 2011
    I was just wondering if when you copy, it would fill your RAM up.

    I mean, HDD itself has cache for just that purpose (e.g. the OWC On-The-Go Pro 750GB Triple Interface Storage Solution
    Mac / PC / FireWire 800 / FireWire 400 / USB 2.0 & 1.1 has 16MB cache
    http://eshop.macsales.com/item/Other World Computing/MS8U7750GB16/)
    (it's my favorite HDD that I'm gonna buy in a few months or sow)

    Well, the 16MB cache is the hard drive's disk buffer. So it's basically ssd (if I'm not mistaken, please tell me if I'm wrong, 'cause I'm not 100% sure)
    (this is how it should work, but it's not tru I think)
    For writhing to an HDD, I don't really know what happens:

    so if you right small amounts of data to it, it will buffer it like RAM and your right task will be done "faster". (If you only look at the HDD, it will be the same time, 'cause it will right it from the cache to the HDD after the transfer is complete, basically, the data has been pushed to the HDD, the MBP says done, but it still will be righting on the HDD)

    I'm sure about the next:
    For reading the cache behaves like this:
    The cache is a component that stores data (that is accessed a lot) so that future requests for that data can be served faster. If the requested data is in the cache, it can be served by simply reading the cache, which is comparatively faster ('cause I think it's ssd like cache). Otherwise (the data has to be read from its original storage location on the HDD, which is comparatively slower (due latency and lower read speeds).

    Please correct me where I'm wrong, and please confirm where I'm correct.
    'Cause I wonna know what's going on. :)

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