Performance vs. Transfer Size

ATTO does a good job of showing us how sequential performance varies with transfer size. Most controllers optimize for commonly seen transfer sizes and neglect the rest. The optimization around 4KB, 8KB and 128KB transfers makes sense given that's what most workloads are bound by, but it's always important to understand how a drive performs across the entire gamut.

The 525's sequential read curve is almost identical to that of the 520. Whatever firmware improvements exist in the 525, they don't seem to obviously impact low queue depth sequential read performance over the 520.

Sequential write performance is a similar story, although the 520 does have a bit of an advantage in 32KB sequential transfers. Overall the 525 and 520 look indistinguishable however.

Random & Sequential Performance Performance Consistency
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  • vcorem - Wednesday, January 30, 2013 - link
  • IanCutress - Wednesday, January 30, 2013 - link

    Mushkin uses a stacked daughter board to achieve 480GB. This is usually ok in a motherboard, but not in a z-height limited mobile device. While it's still electrically mSATA, it is technically outside the mSATA specifications which limit z-height (if I recall correctly).
  • lukarak - Wednesday, January 30, 2013 - link

    What is the chip density in the 768 GB SSD board in a rMBP? Does it have 12?
  • Kristian Vättö - Wednesday, January 30, 2013 - link

    Yup, the 768GB SSD in rMBP has twelve 64GB (8x8GB) packages.

    However, SandForce has much stricter restrictions, the SF-2281/2 can only access up to 64 NAND dies (that's up to 512GB with 8GB dies). Samsung could build a 1TB drive if they wanted to, they just don't see the market for it (yet).
  • lukarak - Wednesday, January 30, 2013 - link

    Thanks for the answer.

    On a slightly related note, the iPad (late 2012) 16 GB, has a single NAND chip, as could be seen in the teardowns, and there doesn't seem to be any room for more. Do you perhaps know, or care to speculate, how the higher capacity ones are configured, especially the new 128 GB version?
  • Kristian Vättö - Wednesday, January 30, 2013 - link

    The 128GB model is most likely using new 128Gb (16GB) NAND dies to enable the higher capacity. You can only stack up to eight dies in a single package, so a higher capacity die was needed before you could go over 64GB (8x 16GB is 128GB).

    At least Samsung and IMFT have 128Gb dies in production but they most likely weren't available in volume when the iPad 4 was initially launched, hence the delay.
  • lukarak - Wednesday, January 30, 2013 - link

    Makes sense, thanks for the insight.
  • SAMSAMHA - Wednesday, January 30, 2013 - link

    hi, Anand

    I am curious what board are you using to test this since none of the desktop board with mSATA that I know has SATA 6Gbps interface.
  • SodaAnt - Wednesday, January 30, 2013 - link

    There are msata to sata conversion boards that work fine because msata and sata are electrically the same.
  • Meaker10 - Wednesday, January 30, 2013 - link

    The msi gt60 can ship with a pair of msata gen3 slots configurable in raid.

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