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.

[ Post a follow-up to this message ]

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.

[ Post a follow-up to this message ]

Hans-Bernhard Bröker wrote:

> Spoon wrote:
> 
> 
>
> 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?
 
>
> 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.

[ Post a follow-up to this message ]

Spoon wrote:

> Hans-Bernhard Bröker wrote:
> 
>
> 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?
> 
>
> 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?
> 
>
> Does the embedded world trust USB more than IDE?
> 
>
> Thanks to Bob Smith for providing a link to such a converter.
>
> Do you know if one can find them easily in Europe?

Anybody?

[ Post a follow-up to this message ]