Sandisk SSD

Discussion in 'MacBook' started by JamesGorman, May 27, 2009.

  1. JamesGorman macrumors 65816

    JamesGorman

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    #1
  2. ppc750fx macrumors 65816

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    #2
    They're MLC drives, so beware. Basically, until I see what sort of numbers these things put up for small random reads/writes, I'm going to assume that their controller sucks compared to Intel's.

    Why would I assume that, you might ask? Because that's been the case for every single MLC drive thus far, without exception.
     
  3. MikhailT macrumors 601

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    You do realize Intel X25-M is MLC right?

    The speed and performance of an SSD has nothing to do with MLC. It has everything to do with the controller and how they interact between the controller and NANDs.

    All the SSDs can have the same exact NANDs but they all won't perform the same because they have different controllers with different method of caching as well.

    Intel's controllers are specifically designed for random IOPS, that's why they are the best on the market. The rest of the controllers were seq IOPS focused and good ones like Indilinx and Samsungs P256 can beat Intel in all areas related to seq transfers. Random IOPS, nothing is close to Intel right now but for most people Indilinx and Samsungs may be enough for them right now.
     
  4. JamesGorman thread starter macrumors 65816

    JamesGorman

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  5. MikhailT macrumors 601

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    #5
    MLC: Multi-level Cell


    It's a type of flash memory cell that can hold more than one bit at a time. Which is why MLC drives are bigger than SLC (Single-Level Cell) drives and also why they have awful write speed. It can not write any bit at random in a cell, it has to write all bits at once to fit the cell. Read speed is always the same between MLC/SLC.
     
  6. JamesGorman thread starter macrumors 65816

    JamesGorman

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    Ok, that makes sense, by bigger do you mean larger capacity? And also, someone pointed out that the intel drives use mlc, so I guess if they're configured right there not all that bad.

    On a side note, even if there write speed was not as fast as an SLC drive, these MLC drives are still a lot faster than traditional HDD's correct?
     
  7. MikhailT macrumors 601

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    #7
    Yes, by bigger, I mean larger capacity.

    X25-M is the MLC series whereas X25-E is the SLC series.

    SSD are in its infancy, everybody is still learning the rope to produce better, faster, cheaper SSDs.

    The NANDs itself will continue to get smaller, faster and cheaper over time with process shrinks as well as the newer and faster standards for it such as the ONFI 2.1/3.0.

    MLC/SLC drives have super low latency, .01ms. Typical HDD are usually 7-10ms (raptors 4-6ms), that means SSD is 700 or more times faster at looking up data than HDD. That's why everybody is always saying that SSD is the biggest performance upgrade for any system, it is very extremely fast at seeking data and that's why SSD are recommended for a boot/application drive.

    A very good SSD (both SLC/MLC) will always be faster than any traditional HD (except in raid). Unfortunately SSDs have performance degradation issue when the drive fills up over time. Writing to a fresh memory cell will always be much faster than writing to already written used memory cell. They can slow down the write speed after all the memory cells are used up. Read speed and latency will always be the same, it is not affected by that. HDD slows down dramatically as the drive fills up in both read/write speed.

    In the near future, the performance degradation will be eliminated by using the TRIM operation. TRIM to SSD is like what defragmentation is to HDD.
     
  8. bolen macrumors 6502

    bolen

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    #8
    The only SSD drive worth buying today is either the Intel X25-M or the OCZ Vertex. Read this article at AnandTech to fully understand the concept, issues and "specialness" about SSD's. I'll grab one of the Intel X25-M 320GB myself once they hit the shelves.

    Don't waste your money on cheap drives with crappy controllers.
     
  9. JamesGorman thread starter macrumors 65816

    JamesGorman

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    The intel drives are super expensive, and besides the only bad controller i heard of was the Jmicron one, and I'm not sure if this drive uses it or not. Id be happy if i got two years out of one of these drives.
     
  10. MikhailT macrumors 601

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    #10
    Sandisk G3 will use Sandisk brand new controller for it. It'll be Sandisk everything including controller, NANDs, cache. We have no idea what kind of performance it'll have. Sandisk keeps hyping up the ExtremeFFS as a method to speed up all random writes by converting it to seq writes. If that is true, they could be seriously competitive against Intel in that area.

    As for Vertex, they use Indilinx controller, a new controller from an unknown start up that was started by ex-Samsung employers and so on. Indilinx so far are the second best alternative to Intel with Samsung P256 controller being the third.

    Unfortunately, right now I wouldn't recommend Vertex for the Macs, they have some issues at the moment which could be fixed by a firmware update. For many people, 10.5.7 fixed most of the issues.

    I have Vertex 120GB, and I have only the Bootcamp incompatibility issue with 10.5.7 fixing the system wake/hibernation issue. Apple claims that they are aware of the bootcamp situation.
     
  11. ppc750fx macrumors 65816

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    #11
    The Intel drives aren't that costly, all things considered...

    Yes, the Barefoot controllers are better than the JMicron ones -- they're better than most conventional drives too -- but they still only have a fraction of the performance of Intel's controller when it comes to random 4K reads/writes.

    The OCZ Summit looks promising, but I still think that OCZ a generation away from really having an MLC offering that's competitive with Intel's when it comes to small random IO ops. Just my 0.02c.
     

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