Solid state hard drive

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to act
as a permanent storage (hard disk). Anyone any experience of this technology
and can comment on performance versus a 'normal' hard disk.

On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to act
as a permanent storage (hard disk). Anyone any experience of this technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)
Actually: very, very limited use, especially if you want to run
'normal' software.

Running all from CF requires an adapted OS. One that levels out
the wearing of CF-cells.

--
Kind regards,
Gerard Bok

"Gerard Bok" wrote in message
...
On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to
act
as a permanent storage (hard disk). Anyone any experience of this
technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)
Actually: very, very limited use, especially if you want to run
'normal' software.

Do you have any comparison performance figures - speed and MTBF?

Running all from CF requires an adapted OS. One that levels out
the wearing of CF-cells.

On Tue, 6 Feb 2007 15:35:06 -0000, "GT"
wrote:

"Gerard Bok" wrote in message
...
On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to
act
as a permanent storage (hard disk). Anyone any experience of this
technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)
Actually: very, very limited use, especially if you want to run
'normal' software.

Do you have any comparison performance figures - speed and MTBF?

They are very dissimilar. Hence, hard to compare.

Harddisks can transfer in excess of 25 MB/sec. That's the current
top-speed for flash. But then: hardly any application really runs
at this speed. (With the exeption of video. For which CF memory
is a poor choise anyway :-)
Harddisks have latency, the time they need to find a spot and
position their heads. CF virtually have none.

MTBF: A harddisk can run for years. Life is limited by the number
of start-stop cylcles.
CF is limited by the number of times a cell can be rewritten.
100.000 cycles for popular SLC NAND chips.
10.000 cycles for high density MLC chips.

Say, for the sake of argument, that you would install 'Windows'.
The area used by the 'swap file' would wear very, very fast :-)

--
Kind regards,
Gerard Bok

On Tue, 06 Feb 2007 14:55:28 GMT, (Gerard
Bok) wrote:

On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to act
as a permanent storage (hard disk). Anyone any experience of this technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)

It would be more accurate to state, "lasts FAR longer than
every hard drive, but lower number of write cycles".



Actually: very, very limited use, especially if you want to run
'normal' software.


Actually: You could run the most popular OS on earth
(WinXP) from one, but you need to do a few things first like
disable the swapfile or use a write filter (as XP Embedded
does (can do)) and you can't install bloated software. It
is slower though, at least the one OP linked.


Running all from CF requires an adapted OS. One that levels out
the wearing of CF-cells.

False, that is handled by the CF controller, the OS cannot
do that. If the OS tried to do it, it would be ignored and
the CF controller still does it automatically.

On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to act
as a permanent storage (hard disk). Anyone any experience of this technology
and can comment on performance versus a 'normal' hard disk.


The only you linked looks to be the PIO-mode (Only) type,
meaning very slow transfer rates. You can get this type at
many places like eBay for about $4. For performance you
should instead seek one that can do DMA and typically being
rarer, costs about $30 and up... though by now they might be
coming from China, on eBay too, which could make them
closer to $4 as the others are.

To use the faster cards you want a CF 3.0 spec'd, CF card.
This allows up to ATA66 mode which is substantially faster
and lower CPU utilization.

Then it depends on the spec of your CF card for read and
write speed. If you buy one fast enough it can give a
mechanical HDD a run for it's money, typically lower
sustained transfer rates on larger files but very low
latency. It really depends on your needs, whether CF-IDE is
viable or not, people tend to choose it for lower
power/heat, smaller size, reliability, instead of
performance or capacity. To get the best performance and
capacity too it requires spending several hundred dollars
for only a few dozen GB of space. Some people can run WinXP
from a 10GB HDD though, and others seem to fill up their
200GB+, it depends on the user and their needs.

If you just want to try it out and don't care about the
performance (can accept PIO mode for some basic embedded
system use), pick up the $4 adapter from ebay and a slower
2GB CF card often available for about $10-20 after rebate.
It isn't what you'd want to run windows, but for a router or
several other single-purpose, unattended systems it is
usable.

"Gerard Bok" wrote in message
...
On Tue, 6 Feb 2007 15:35:06 -0000, "GT"
wrote:

"Gerard Bok" wrote in message
...
On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to
act
as a permanent storage (hard disk). Anyone any experience of this
technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)
Actually: very, very limited use, especially if you want to run
'normal' software.

Do you have any comparison performance figures - speed and MTBF?

They are very dissimilar. Hence, hard to compare.

Harddisks can transfer in excess of 25 MB/sec. That's the current
top-speed for flash. But then: hardly any application really runs
at this speed. (With the exeption of video. For which CF memory
is a poor choise anyway :-)
Harddisks have latency, the time they need to find a spot and
position their heads. CF virtually have none.

MTBF: A harddisk can run for years. Life is limited by the number
of start-stop cylcles.
CF is limited by the number of times a cell can be rewritten.
100.000 cycles for popular SLC NAND chips.
10.000 cycles for high density MLC chips.

Say, for the sake of argument, that you would install 'Windows'.
The area used by the 'swap file' would wear very, very fast :-)


I was thinking about using such a device for my work: C++ development. Lots
of small files and lots of file reads and writes to object files during a
build. The hard disk always sounds very busy, so I thought this device with
a 2GB or 4GB Sandisk Extreme III (£80) might speed things up. I guess that
card will be high density, given its size, so 10,000 cycles doesn't sound
very much! Although it does come with a lifetime warranty.

"kony" wrote in message
news
On Tue, 06 Feb 2007 14:55:28 GMT, (Gerard
Bok) wrote:

On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to
act
as a permanent storage (hard disk). Anyone any experience of this
technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)

It would be more accurate to state, "lasts FAR longer than
every hard drive, but lower number of write cycles".

But he goes on to say that compactFlash is 'typically good' for 10.000
cycles for high density MLC chips. I don't know how this relates to my
situation, but it doesn't sound very long to me!

Lets discuss a more useful example: If an 8GB compactFlash (20MB/s) unit
were used as a windows system drive (no swap file), maybe 1.5 boots per day
and 8 hours of windows use per day, how long do we all think it would
typically last? And how would its performance compare to a Western Digital
Caviar SE16, 250GB, 16MB cache, WD2500KS?

On Tue, 06 Feb 2007 12:06:53 -0500, kony wrote:

On Tue, 06 Feb 2007 14:55:28 GMT, (Gerard
Bok) wrote:

On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to act
as a permanent storage (hard disk). Anyone any experience of this technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)

It would be more accurate to state, "lasts FAR longer than
every hard drive, but lower number of write cycles".

It all depends on what you mean by 'lasting'.
Most parts last forever. If you don't use them, that is :-)

Running all from CF requires an adapted OS. One that levels out
the wearing of CF-cells.

False, that is handled by the CF controller, the OS cannot
do that. If the OS tried to do it, it would be ignored and
the CF controller still does it automatically.

Not as 'false' as you may expect :-)
Common CFS functions provide for 'finding' a not-to-much-used
spot for a file that is about to be written. Which is good.

But a real Flash-friendly FS would eventually move files that
only were written once to another spot, so that the latend
write-capability of it's space could be fully exploited.

As for OP's application: I would suggest some experimenting with
a RAM-disk.

--
Kind regards,
Gerard Bok

On Tue, 6 Feb 2007 17:33:57 -0000, "GT"
wrote:

"kony" wrote in message
news
On Tue, 06 Feb 2007 14:55:28 GMT, (Gerard
Bok) wrote:

On Tue, 6 Feb 2007 14:11:09 -0000, "GT"
wrote:

Just found this adapter:

http://www.cfide.co.uk/compact_flash...fide_fdd.shtml

It lets you connect a compactFlash memory card to your IDE interface, to
act
as a permanent storage (hard disk). Anyone any experience of this
technology
and can comment on performance versus a 'normal' hard disk.

Quick. Expensive. Fast. Size-limited.
Not nearly as lang lasting as even the cheapest harddisk :-)

It would be more accurate to state, "lasts FAR longer than
every hard drive, but lower number of write cycles".

But he goes on to say that compactFlash is 'typically good' for 10.000
cycles for high density MLC chips. I don't know how this relates to my
situation, but it doesn't sound very long to me!


If one of your concerns is # of write cycles, why would you
use one with MLC chips? Regardless, AFAIK they're all at
around 100K cycles or more now, not 10K.

One of the keys to longer life is not to buy one barely
bigger than you need. For example, suppose you had 800MB of
static files, and (roughly, rounding down) 200MB of free
space on a 2GB card. Now suppose you have temporary
internet files or whatever... on a 1GB CF card, the
wear-leveling feature will only be able to wear-level among
the remaining 200MB of free space, so if you had 50MB to
write to the card over and over again, it would only take 4
passes to have written to all of that 200MB, one time.

Now contrast that with using a 2GB card, still 800MB of
static files. You have (again, roughly) 1200MB free, so
with that wear-leveling you would have closer to 24
passes... you just realized a sixfold increase by having a
card with a lot more free space.




Lets discuss a more useful example: If an 8GB compactFlash (20MB/s) unit
were used as a windows system drive (no swap file), maybe 1.5 boots per day
and 8 hours of windows use per day, how long do we all think it would
typically last? And how would its performance compare to a Western Digital
Caviar SE16, 250GB, 16MB cache, WD2500KS?

It depends entirely on how you use the system. CF card may
not be the right answer for your generic (typical) desktop
Windows activites, primarily because Windows was designed
with the idea that it could incessantly write to the HDD
without any action on the user's part to cause it.

As I'd already written, you could use an EWF, enhanced write
filter, or a ramdrive for many things, but only you can know
what size files you'll be writing that need to be retained
inbetween reboots. Suppose for example you had a networked
fileserver you could store most things on, even run some
applications from, you have greatly decreased your need for
disk space on the PC, though the hard drive will be faster
(yet another variable, how much main system memory you have
since quite a lot can be used as a filecache).

As for how long it'll last, same story - depends on how you
use the system. If you just tried to pretend it's a hard
drive, it might not last more than a few weeks or months,
but doing basic things like disabling logging and pagefile
can go a long way, or using the EWF, you've reduced that
onto the point where there's nothing writing to it after
windows boot loader takes over, unless you commit something
to be written by manual intervention/choice. Another option
might be to have a 2nd CF card, that one used for pagefile,
logging, temporary internet files, etc, and replaced more
often.

I suggest you get your feet wet using CF for embedded or
single-purpose systems, particularly where there isnt a lot
of local file I/O after the OS has finished booting.

Frankly, Windows XP isn't the best OS to run from a flash
media, in you want to run XP you have to take the good with
the bad, and the bad means it devours system resources like
perpetual drive access, but we'd have to point the finger at
application developers too, many made nice compact apps
during earlier eras, but when they updated to support XP
(for example), they also tacked on a lot of functionality
that many people don't use, growing the app to several times
it's former size. Now that flash media is getting more cost
effective there is a growing interest in alternative apps
that can run from a thumbdrive, though you wouldnt' have to
run them from one, typically they'd be well suited to a CF -
IDE arrangement too.