SDXC as poor mans SSD on MBP

Discussion in 'MacBook Pro' started by digipro00, Feb 1, 2012.

  1. digipro00 macrumors newbie

    Feb 1, 2012
    I'm need to buy a new MBP, and I am torn over the storage capacity to get in there. I do a lot of pro-audio work, so for a long time now I have been lugging around firewire drives to record my sessions directly onto. With the new MBP i hope to buy, i was considering getting it with the 128gb SSD on which i woud install all my Apps, and then replace the Optical Drive with a 1TB hard drive that i could use to record all my audio work, and avoid having to carry around extra drives.

    Thennn i saw the SDXC slot, which got me thinking. Basically, i want to see if the SDXC can act as a drive at least as fast as an external firewire drive, or better yet as fast as a traditional hard drive in the optical bay. Basically, can it function as a somewhat high performing drive? Right now i actually run my old MBP completely through an SSD in the PCI Express card slot, and it gave me a definite boost over the regular startup drive. (best $100 ever) I know you can boot off of that SDXC, but I'm just not sure how the guys at apple wired these SDXC slots for speed.

    So what do you guys think? Can we all look at SDXC as being a second internal HD? Thanks!
  2. ZZ Bottom macrumors 6502a

    Apr 14, 2010
    Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A405 Safari/7534.48.3)

    It's a good thing not all of us accept such insulting responses. If you know why not briefly explain why...

    OP keep in mind one of the advantages FireWire has always had over controllers like USB is it is reliably steady. Traditionally the SD slots on macs have been based on USB controllers, but I have seen a couple mention that the current gen of MBPs use sata bus. Don't know if there's truth to this.
  3. phyrexia macrumors 6502a

    Sep 3, 2010
    Speed Class Rating

    32GB SDHC card
    The Speed Class Rating is the official unit of speed measurement for SD cards. The class number guarantees a minimum write speed as a multiple of 8 Mbit/s (1 MB/s). The SDA defines several speed class ratings, but manufacturers may claim conformance to those ratings without independent verification.
    The host device can read a card's speed class, unlike the earlier "×" speed ratings. A device can warn the user if the card reports a speed class that falls below an application's minimum need.[39]
    These are the ratings of all currently available cards:[40][41]
    Class Speed
    Class 2 2 MB/s
    Class 4 4 MB/s
    Class 6 6 MB/s
    Class 10 10 MB/s

    (seven seconds of research)
  4. dmccloud macrumors 6502a


    Sep 7, 2009
    Anchorage, AK
    In my experience (on both Mac and Windows machines), you get speeds comparable to a USB flash drive - nowhere near what you get from an internal HDD or FW 800 drive. This is independent of the class(speed) of the card.
  5. psykick5 macrumors 6502

    Sep 4, 2011
    Average HDD - 300MB/s (buffer to computer)
    SSD - 600MB/s+
    SD card - 10MB/s

    No bueno.
  6. thundersteele macrumors 68030

    Oct 19, 2011

    It's hard to find reliable information and benchmarks for SD cards that would address exactly this question. One reason is e.g. that many benchmarks are being done using USB 2.0 card readers, so whatever happens, it will always be slow.

    However the following is easy to find:
    - from wikipedia, the fastest speed classification is 10 MB/s sustained read/write rates
    - SD(XX) cards are optimized for camera use... i.e. for sequential read/write performance. Random read/writes are awfully slow.

    Beyond that:
    - I've seen SD cards advertised with speeds up to 60 MB/s - still slower than an average HDD
    - access times might be faster (no mechanical parts)
    - no smart controller that avoids wearing out parts of the storage, no TRIM support: performance might degrade a lot over time
    - sticks out of the side of the MBP - not very safe, and inconvenient
    - lower quality NANDs compared to what goes into a SSD
    - not really cheap when you look at the cost per GB

    Currently either SSD + optibay or SSD + external are viable choices if a larger SSD is too expensive.
  7. grahamnp macrumors 6502a

    Jun 4, 2008
    System report shows that the SD slot has a 2.5GT/s x1 interface which means 300+ MB/s but you're still limited by the card speed so no luck there.

    SDXC cards are not cheap. A 64GB card is $ 70-110 which puts it in SATA II SSD territory and a 128GB card is more expensive than a 128GB SSD. If installing the optibay is not an issue, I think that is the only option for having an SSD + HDD.

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