DOC, DOM, SSD - Storage

This is a discussion on DOC, DOM, SSD - Storage ; Hello, What do people have in mind when they talk about : DOC (Disk On Chip) DOM (Disk On Module) SSD (Solid State Drive) Are they different technologies? A few links, for my own reference: http://en.wikipedia.org/wiki/Solid_state_disk http://en.wikipedia.org/wiki/Disk_on_module I'm looking to ...

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Thread: DOC, DOM, SSD

  1. DOC, DOM, SSD

    Hello,

    What do people have in mind when they talk about:

    DOC (Disk On Chip)
    DOM (Disk On Module)
    SSD (Solid State Drive)

    Are they different technologies?

    A few links, for my own reference:
    http://en.wikipedia.org/wiki/Solid_state_disk
    http://en.wikipedia.org/wiki/Disk_on_module

    I'm looking to replace a conventional hard disk drive with something
    that has no moving parts (and a PATA connector).

    This article states: "The average cost for a competitive SSD design in
    the consumer market is currently about $17 per GB of storage."

    http://anandtech.com/storage/showdoc.aspx?i=2982

    Is that true for 1 and 2 GB parts? In other words, are there $20 and $40
    1-GB and 2-GB SSD units available?

    Regards.

  2. Re: DOC, DOM, SSD

    Spoon wrote:

    > What do people have in mind when they talk about:


    > DOC (Disk On Chip)
    > DOM (Disk On Module)
    > SSD (Solid State Drive)


    That, as always, depends quite a bit on which "people" you're going to
    ask. If the three terms were to be force-fitted with separate meanings,
    those could usefully be:

    DOC: a file-system in an actual chip package, i.e. in a typical chip
    package (DIP, LQFP, BGA, whatever), meant to be soldered in place.

    DOM: like DOC, but in a standardized socket, designed to be
    exchangeable. Compact Flash, SD, MD, you name it.

    SSD: similar to DOM, but connected exactly like an actual hard drive
    would be. Things like that were made for those corner cases where all
    mechanical drives failed to quite meet the need. They're also just
    about perfect to benchmark a SCSI controller with.

    A USB stick would land smack in the middle between DOM and SSD, given
    that USB has cut itself quite a chunk out of the market for mass storage
    device interfaces.

    > Is that true for 1 and 2 GB parts? In other words, are there $20 and $40
    > 1-GB and 2-GB SSD units available?


    Quite possibly. CompactFlash, in particular, is so similar to PATA that
    it doesn't really take more than a socket converter to use any CF card
    as a SSD.

  3. Re: DOC, DOM, SSD

    Hans-Bernhard Bröker wrote:

    > Spoon wrote:
    >
    >> What do people have in mind when they talk about:

    >
    >> DOC (Disk On Chip)
    >> DOM (Disk On Module)
    >> SSD (Solid State Drive)

    >
    > That, as always, depends quite a bit on which "people" you're going to
    > ask. If the three terms were to be force-fitted with separate meanings,
    > those could usefully be:
    >
    > DOC: a file-system in an actual chip package, i.e. in a typical chip
    > package (DIP, LQFP, BGA, whatever), meant to be soldered in place.


    As far as I understand, Disk On Chip devices need their own driver,
    they can't be accessed (??) by the generic IDE layer.

    Linux has an entire section dedicated to "Memory Technology Device".

    config MTD

    Memory Technology Devices are flash, RAM and similar chips, often
    used for solid state file systems on embedded devices. This option
    will provide the generic support for MTD drivers to register
    themselves with the kernel and for potential users of MTD devices
    to enumerate the devices which are present and obtain a handle on
    them. It will also allow you to select individual drivers for
    particular hardware and users of MTD devices. If unsure, say N.

    http://lxr.linux.no/source/drivers/mtd/
    http://lxr.linux.no/source/drivers/mtd/Kconfig
    http://lxr.linux.no/source/drivers/mtd/chips/Kconfig
    http://lxr.linux.no/source/drivers/mtd/devices/Kconfig
    [...]

    If I understand correctly, these devices do not try to appear like
    a conventional generic IDE hard disk drive. Is that correct?

    > DOM: like DOC, but in a standardized socket, designed to be
    > exchangeable. Compact Flash, SD, MD, you name it.


    I was under the impression that Disk On Module devices, unlike Disk On
    Chip devices, included additional logic to make them appear like a
    conventional hard disk drive. Perhaps I am mistaken?

    > SSD: similar to DOM, but connected exactly like an actual hard drive
    > would be. Things like that were made for those corner cases where all
    > mechanical drives failed to quite meet the need. They're also just
    > about perfect to benchmark a SCSI controller with.
    >
    > A USB stick would land smack in the middle between DOM and SSD, given
    > that USB has cut itself quite a chunk out of the market for mass storage
    > device interfaces.


    Does the embedded world trust USB more than IDE?

    >> Is that true for 1 and 2 GB parts? In other words, are there $20 and
    >> $40 1-GB and 2-GB SSD units available?

    >
    > Quite possibly. CompactFlash, in particular, is so similar to PATA that
    > it doesn't really take more than a socket converter to use any CF card
    > as a SSD.


    Thanks to Bob Smith for providing a link to such a converter.

    Do you know if one can find them easily in Europe?

    Regards.

  4. Re: DOC, DOM, SSD

    Spoon wrote:

    > Hans-Bernhard Bröker wrote:
    >
    >> Spoon wrote:
    >>
    >>> What do people have in mind when they talk about:

    >>
    >>> DOC (Disk On Chip)
    >>> DOM (Disk On Module)
    >>> SSD (Solid State Drive)

    >>
    >> That, as always, depends quite a bit on which "people" you're going to
    >> ask. If the three terms were to be force-fitted with separate
    >> meanings, those could usefully be:
    >>
    >> DOC: a file-system in an actual chip package, i.e. in a typical chip
    >> package (DIP, LQFP, BGA, whatever), meant to be soldered in place.

    >
    > As far as I understand, Disk On Chip devices need their own driver,
    > they can't be accessed (??) by the generic IDE layer.
    >
    > Linux has an entire section dedicated to "Memory Technology Device".
    >
    > config MTD
    >
    > Memory Technology Devices are flash, RAM and similar chips, often
    > used for solid state file systems on embedded devices. This option
    > will provide the generic support for MTD drivers to register
    > themselves with the kernel and for potential users of MTD devices
    > to enumerate the devices which are present and obtain a handle on
    > them. It will also allow you to select individual drivers for
    > particular hardware and users of MTD devices. If unsure, say N.
    >
    > http://lxr.linux.no/source/drivers/mtd/
    > http://lxr.linux.no/source/drivers/mtd/Kconfig
    > http://lxr.linux.no/source/drivers/mtd/chips/Kconfig
    > http://lxr.linux.no/source/drivers/mtd/devices/Kconfig
    > [...]
    >
    > If I understand correctly, these devices do not try to appear like
    > a conventional generic IDE hard disk drive. Is that correct?
    >
    >> DOM: like DOC, but in a standardized socket, designed to be
    >> exchangeable. Compact Flash, SD, MD, you name it.

    >
    > I was under the impression that Disk On Module devices, unlike Disk On
    > Chip devices, included additional logic to make them appear like a
    > conventional hard disk drive. Perhaps I am mistaken?
    >
    >> SSD: similar to DOM, but connected exactly like an actual hard drive
    >> would be. Things like that were made for those corner cases where all
    >> mechanical drives failed to quite meet the need. They're also just
    >> about perfect to benchmark a SCSI controller with.
    >>
    >> A USB stick would land smack in the middle between DOM and SSD, given
    >> that USB has cut itself quite a chunk out of the market for mass
    >> storage device interfaces.

    >
    > Does the embedded world trust USB more than IDE?
    >
    >>> Is that true for 1 and 2 GB parts? In other words, are there $20 and
    >>> $40 1-GB and 2-GB SSD units available?

    >>
    >> Quite possibly. CompactFlash, in particular, is so similar to PATA
    >> that it doesn't really take more than a socket converter to use any CF
    >> card as a SSD.

    >
    > Thanks to Bob Smith for providing a link to such a converter.
    >
    > Do you know if one can find them easily in Europe?


    Anybody?

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