write endurance - solid state flash drives, windows xp, virtualmemory

On Wed, 4 Jun 2008 17:38:36 -0700 (PDT),
"jameshanley39@yahoo.co.uk" <jameshanley39@yahoo.co.uk>
wrote:

>On 4 Jun, 00:32, kony <s...@spam.com> wrote:
><snip>
>> Revision is very important for the intended use as a
>> replacement for *a hard drive on a Compact Flash - IDE
>> adapter because it determines whether the card will operate
>> in UDMA mode. *Some cards rated for 150X (which is about
>> 22MB/s) can't even exceed 6MB/s when connected to a CF-IDE
>> adapter in PIO mode, and use quite a lot of CPU time to do
>> it while UDMA mode doesn't. *It makes a night and day
>> difference in the performance, changing an extremely
>> sluggish system into one that's fairly snappy so long as the
>> file transfers aren't very large or huge numbers of tiny
>> files.
>
>I see how PIO is bad because of its CPU utilization. But in terms of
>speed.. UDMA is generally faster. But there are fast PIO and slow
>UDMA..

There's no UDMA (0) slower than the fastest PIO. Mainly the
point is, AFAIK nobody would pair up the low end cheap flash
chips that are slow, with the premium UDMA capable
controller, though they'll be more likely to pair the
fastest chips up with the premium controller. This also
tends to be true because of customer demand, higher
performance more sophisticated equipment would be the most
likely to use UDMA mode instead of a camera, though I
suppose these days that generalization is changing, a lot of
purpose built ICs do far more than they used to.

Generally we can ignore all these issues and just remember
one thing - you absolutely must have a card with CF3 or 4
spec operating in UDMA mode if you want it more than
sluggish.

Keep in mind, any modern flash chips can achieve over 27MB/s
read speed, including the low-end, if only they have the
right controller and for your purposes that means it can't
operate in PIO mode even if what I was about to write next
wasn't true.


>Howcome you keep referring to PIO as 6MB/s. Why wouldn't PIO cards go
>faster, like 16.7MB/s. Is it because you are saying the cheap cards
>are PIO mode 1.

I'm saying that I didn't care enough to find out why they
only achieved 6MB/s, apparently they only supported a lower
PIO mode - on several different motherboards so it would
tend to implicate the cards. These were mostly 512MB to 2GB
cards I had leftover from an old camera.


>I suppose ATA(ATA/IDE connector) doesn't support Modes 5,6. Since that
>is specific to CF. But it would support Mode 4 PIO I would think.
>16.7MB/s

I don't understand why you are spending time pondering the
very cards you don't want to use if performance is
important. It wouldn't be surprising, in the low end
cards, for the manufacturer to only support the bare minimum
it takes to qualify as a "Compact Flash" card, particularly
since many cameras aren't using them in PIO mode. That
could be seen as a good thing, as today you can get a 2GB
low end card almost for nothing, $15 or less generally, but
it might be the equivalent of comparing a zip drive to a
hard drive when it comes to performance running a large(r)
OS from it on an ATA controller. Even Win98 using Win98
shell a la 98Lite, an installation taking under 200MB drive
space and about a couple dozen MB memory, is a bit sluggish
running from a low end CF card in PIO mode.


>
>Another oddity is that sandisk Extreme IV cards say UDMA mode 4. But
>have a max R/W of up to 40MB/s (266x), I guess they adverise as 266x,
>so it's a max. The oddity though, is they may as well be on UDMA mode
>3. !!

This is the same as with any other drive, you want the
interface bandwidth to be as high as possible - modern spec,
no matter whether the actual performance could've been done
with some slower interface. It wold serve no useful purpose
for it to be CF3 instead, CF4 is the modern spec and thus
any modern card pretending to be high performance should
adhere to that spec.

I'm going to back up and say again what you seemed to miss.
Don't think about these things. Think about only:

CF4 spec
SLC chips
Max read speed the budget can afford
(in this order of importance)





>And if that's the max speed, I wonder what the minimum be like
>
>ref-
>
>PIO
>Mode 6 - 25MB/s <--- CF2
>Mode 5 - 20MB/s <-- CF2
>Mode 4 - 16.7MB/s <-ATA
>Mode 3 – 11.1MB/s <-ATA
>Mode 2 – 8.3MB/s <-ATA
>Mode 1 – 5.2MB/s <-ATA
>Mode 0 - 3.3MB/s <-- ATA
>
>UDMA
>Mode 5 - 100MB/s <-- ATA/ATAPI
>Mode 4 - 66.7 MB/s <-- ATA/ATAPI
>Mode 3 – 44.4MB/s <-- ATA/ATAPI
>Mode 2 – 33.3MB/s <-- ATA/ATAPI
>Mode 1 - 25MB/s <-- ATA/ATAPI
>Mode 0 - 16.7MB/s <-- ATA/ATAPI
>
>http://en.wikipedia.org/wiki/Programmed_input/output
>(better than pcguide PIO link. which is missing mode 0 and modes 5,6
>
>http://www.pcguide.com/ref/hdd/if/ide/modes_UDMA.htm
>pcguide UDMA link.

You have no guarantee about any mode any card uses unless it
clearly specifies it. However, what we can assume is that
something that makes a CF card more valuable is something
the manufacturer will not overlook mentioning, ie - if it is
CF3 or 4 spec. and the inherant support those mandate.
Beyond that, your choices are really quite limited since you
want not to spend a lot, with the higher cost being the
primary thing keeping many from moving to flash based
storage.

On Jun 5, 4:24*am, kony <s...@spam.com> wrote:
> On Wed, 4 Jun 2008 17:38:36 -0700 (PDT),
> "jameshanle...@yahoo.co.uk" <jameshanle...@yahoo.co.uk>
> wrote:
>
>
>
>
>
> >On 4 Jun, 00:32, kony <s...@spam.com> wrote:
> ><snip>
> >> Revision is very important for the intended use as a
> >> replacement for *a hard drive on a Compact Flash - IDE
> >> adapter because it determines whether the card will operate
> >> in UDMA mode. *Some cards rated for 150X (which is about
> >> 22MB/s) can't even exceed 6MB/s when connected to a CF-IDE
> >> adapter in PIO mode, and use quite a lot of CPU time to do
> >> it while UDMA mode doesn't. *It makes a night and day
> >> difference in the performance, changing an extremely
> >> sluggish system into one that's fairly snappy so long as the
> >> file transfers aren't very large or huge numbers of tiny
> >> files.
>
> >I see how PIO is bad because of its CPU utilization. But in terms of
> >speed.. UDMA is generally faster. But there are fast PIO and slow
> >UDMA..
>
> There's no UDMA (0) slower than the fastest PIO. *Mainly the
> point is, AFAIK nobody would pair up the low end cheap flash
> chips that are slow, with the premium UDMA capable
> controller, though they'll be more likely to pair the
> fastest chips up with the premium controller. *This also
> tends to be true because of customer demand, higher
> performance more sophisticated equipment would be the most
> likely to use UDMA mode instead of a camera, though I
> suppose these days that generalization is changing, a lot of
> purpose built ICs do far more than they used to.
>
> Generally we can ignore all these issues and just remember
> one thing - you absolutely must have a card with CF3 or 4
> spec operating in UDMA mode if you want it more than
> sluggish. *
>
> Keep in mind, any modern flash chips can achieve over 27MB/s
> read speed, including the low-end, if only they have the
> right controller and for your purposes that means it can't
> operate in PIO mode even if what I was about to write next
> wasn't true.
>
> >Howcome you keep referring to PIO as 6MB/s. Why wouldn't PIO cards go
> >faster, like 16.7MB/s. *Is it because you are saying the cheap cards
> >are PIO mode 1.
>
> I'm saying that I didn't care *enough to find out why they
> only achieved 6MB/s, apparently they only supported a lower
> PIO mode - on several different motherboards so it would
> tend to implicate the cards. *These were mostly 512MB to 2GB
> cards I had leftover from an old camera.
>
> >I suppose ATA(ATA/IDE connector) doesn't support Modes 5,6. Since that
> >is specific to CF. But it would support Mode 4 PIO I would think.
> >16.7MB/s
>
> I don't understand why you are spending time pondering the
> very cards you don't want to use if performance is
> important. * *It wouldn't be surprising, in the low end
> cards, for the manufacturer to only support the bare minimum
> it takes to qualify as a "Compact Flash" card, particularly
> since many cameras aren't using them in PIO mode. *That
> could be seen as a good thing, as today you can get a 2GB
> low end card almost for nothing, $15 or less generally, but
> it might be the equivalent of comparing a zip drive to a
> hard drive when it comes to performance running a large(r)
> OS from it on an ATA controller. *Even Win98 using Win98
> shell a la 98Lite, an installation taking under 200MB drive
> space and about a couple dozen MB memory, is a bit sluggish
> running from a low end CF card in PIO mode.
>
>
>
> >Another oddity is that sandisk Extreme IV cards say UDMA mode 4. But
> >have a max R/W of up to 40MB/s (266x), I guess they adverise as 266x,
> >so it's a max. The oddity though, is they may as well be on UDMA mode
> >3. !!
>
> This is the same as with any other drive, you want the
> interface bandwidth to be as high as possible - modern spec,
> no matter whether the actual performance could've been done
> with some slower interface. *It wold serve no useful purpose
> for it to be CF3 instead, CF4 is the modern spec and thus
> any modern card pretending to be high performance should
> adhere to that spec.
>
> I'm going to back up and say again what you seemed to miss.
> Don't think about these things. *Think about only:
>
> CF4 spec
> SLC chips
> Max read speed the budget can afford
> (in this order of importance)
>
>
>
>
>
> >And if that's the max speed, I wonder what the minimum *be like
>
> >ref-
>
> >PIO
> >Mode 6 - 25MB/s <--- CF2
> >Mode 5 - 20MB/s <-- CF2
> >Mode 4 - 16.7MB/s <-ATA
> >Mode 3 – 11.1MB/s <-ATA
> >Mode 2 – 8.3MB/s <-ATA
> >Mode 1 – 5.2MB/s <-ATA
> >Mode 0 - 3.3MB/s <-- ATA
>
> >UDMA
> >Mode 5 - 100MB/s <-- ATA/ATAPI
> >Mode 4 - 66.7 MB/s <-- ATA/ATAPI
> >Mode 3 – 44.4MB/s <-- ATA/ATAPI
> >Mode 2 – 33.3MB/s <-- ATA/ATAPI
> >Mode 1 - 25MB/s <-- ATA/ATAPI
> >Mode 0 - 16.7MB/s <-- ATA/ATAPI
>
> >http://en.wikipedia.org/wiki/Programmed_input/output
> >(better than pcguide PIO link. which is missing mode 0 and modes 5,6
>
> >http://www.pcguide.com/ref/hdd/if/ide/modes_UDMA.htm
> >pcguide UDMA link.
>
> You have no guarantee about any mode any card uses unless it
> clearly specifies it. *However, what we can assume is that
> something that makes a CF card more valuable is something
> the manufacturer will not overlook mentioning, ie - if it is
> CF3 or 4 spec. and the inherant support those mandate.
> Beyond that, your choices are really quite limited since you
> want not to spend a lot, with the higher cost being the
> primary thing keeping many from moving to flash based
> storage.-

thanks.. v good/useful discussion.