Fastest Storage Media?

[Khufu1]

I was wondering, other than RAM, what is the fastest storage media type on the PPC? Primarily, I am looking at CF versus SD. Does an SD versus SDIO slot make a difference? Do the new "high-speed" fancy pants CF memory perform better than Joe Blow CF memory? I am also assuming that anything through the PC slot is either really really slow or just sucks down too much power.
Thanks,
Khufu1

[bendigo]

I heard that SD is not as fast as CF memory ...

maybe someone can corret me...

~cheers
bendigo

[torring]

I think CF is potentially faster than SD, but in practice I find SD works better than CF in a PocketPC because the PocketPC can access the SD card faster than a CF-card, and by that I mean the from turning on the device until you can run a program.

I think the problem with CF, in this respect, is the fact that it has the controller on the card, whereas the SD card uses a controller on the PocketPC.

Some people may have noticed that icons of programs installed on CF do not appear on the start menu after a reset. This is not a problem with SD.

Running programs from the SD card is just as fast as from CF in all other respects.

The observations above are from a Casio E200, Toshiba 310, Ipaq 3660 and Medion PocketPC.

[ux4484]

from:http://www.geocities.com/pocketpcinfo/

Which storage card is faster? - With many Pocket PC devices offering both a CF Card and SD Card for potential storage, which is faster? Below are some transfer rate numbers taken from the www.ce-mobil.de web site:

http://www.geocities.com/pocketpcinfo/images/news_nov12_image1.gif

CF Card Type I - 6 MB/sec
CF Card Type II - 6 MB/sec
MMC Card - 2.5 MB/sec
SD Card - 10 MB/sec

I imagine it can be device dependant too

[Kati Compton]

And I was under the impression that it depended also on SD size.

[bendigo]

further on the question of which storage media is fastest....

Why are there so many different mediums???
Just look at digital cameras with smartmedia being phased out and xD introduced...Sony with their memory stick, memory stick duo and possibly another format.... SD/MMC cards and CF cards...microdrives...

It seems that PocketPC's are settling with the SD format... but is this the fastest and most efficient??

~cheers

[Freezer]

Hi ya

The speed of Compact Flash is determined by a controller chip embedded in the flash card itself.

SD/MMC cards are limited to the speed that the host device can transfer at.

SD can be x4 quicker than MMC

CF - it depends on the controller used in the card itself. The new x25 cards are blindingly fast.

[WyattEarp]

Although CF can go up x25, I believe it was intended to increase the speed of picture taking to bring it up to par with film not running programs and accessing files. There has been no major difference in access speeds for regular information viewing from what I have read on various forums.

[mashtim]

I might be mistaken, but I think the issue goes a bit deeper. What I mean is as follows:

Although SD may be 10mb/sec vs 6mb/sec for CF, many SD slots are also MMC-compatible. Because of this (or maybe just to keep prices down, I'm not sure), the SD slots on the devices are rated more like 4-5mb/sec. Therefore, you should be more concerned with the rates in each individual device rather than with generic flash-card rates. Whether or not the rates change if the slot is SD or SDIO, I am not sure.

On a side-note, though, if possible, I would suggest getting a device with SDIO, rather than plain-jane SD. This is simply because while it may be a while coming the industry seems to be moving away from CF and towards SD for their I/O offerings.

[seanturner]

I've done some speed tests and found that for copying a file even the application you use has an effect on the speed. Here are my results:

http://www.pdajunkie.net/wirelessinetspeedtest.htm

This is just for SD and Wi-FI unfortunately. I used a 128MB sd card for the tests, but, I'll compare them with a 64MB card sometime next week hopefully...

[WyattEarp]

I might be mistaken, but I think the issue goes a bit deeper. What I mean is as follows:

Although SD may be 10mb/sec vs 6mb/sec for CF, many SD slots are also MMC-compatible. Because of this (or maybe just to keep prices down, I'm not sure), the SD slots on the devices are rated more like 4-5mb/sec. Therefore, you should be more concerned with the rates in each individual device rather than with generic flash-card rates. Whether or not the rates change if the slot is SD or SDIO, I am not sure.

On a side-note, though, if possible, I would suggest getting a device with SDIO, rather than plain-jane SD. This is simply because while it may be a while coming the industry seems to be moving away from CF and towards SD for their I/O offerings.


While you are right, I was just referring to the SD card side of the story.
The real bottleneck in speed is in the 4MB limit currently in the SD slot of PPCs. As far as SD vs SDIO there should be no difference nor have I read anywhere that there is.

[dotcomguy]

From what I have read so far, compact flash is faster, but some cards could be slower. Does this mean, if I buy a cheap CF card, it could potentially be slower than other CF cards? I also have read that the speed of Secure Digital cards depends on the device. With something such as an e740, can anyone tell me if the CF would still be faster than the SD? I'm looking at both media right now, but want to make the right choice. ;)

[Pony99CA]

And I was under the impression that it depended also on SD size.
I've heard that, too. Here's my understanding:

<= 128 MB: 2 Mbps
256 & 512 MB: 10 Mbps
>= 1 GB: 20 Mbps

I also understand that MMC-compatibility mode uses 1-bit transfers vs. 4-bit transfers that SD is capable of. That's probably why that data posted by ux4484 listed MMC as 2.5 Mbps and SD as 10 Mbps. (Those were probably maximum speeds at the time; if I go to that German site, they say "bis zu" 10 Mbps, which probably means "up to".) That means that devices that run in MMC-compatibility mode won't take full advantage of SD cards (like my iPAQ 3870 :-().

If all of the above is correct, I wonder if my iPAQ will always get the 0.5 Mbps that my 128 MB SD card gets even if I upgrade to a 256 MB card, or if I'll see a 5x improvement in speed. I'll find out soon enough, I hope; I ordered a 256 MB card. :-)

Steve

[Janak Parekh]

If all of the above is correct, I wonder if my iPAQ will always get the 0.5 Mbps that my 128 MB SD card gets even if I upgrade to a 256 MB card, or if I'll see a 5x improvement in speed. I'll find out soon enough, I hope; I ordered a 256 MB card. :-)
Steve, don't you have a 3870? Our 3870's are only capable of 1-bit speeds. If you get any performance improvements let us know. :)

--janak

[dotcomguy]

And I was under the impression that it depended also on SD size.
I've heard that, too. Here's my understanding:

<= 128 MB: 2 Mbps
256 & 512 MB: 10 Mbps
>= 1 GB: 20 Mbps

I'm still torn between a 256 CF and a 256 SD. If this is true, they would both offer the same performance then, right?

Does anyone have a link to an article or benchmark to confirm this? I'm trying to make a good informed decision. :)

[seanturner]

Well, I did some speed testing with my iPaq 5455 and my 64MB SD card, and copying a file from the SD card to RAM, I get 381KB/sec.

[Pony99CA]

Steve, don't you have a 3870? Our 3870's are only capable of 1-bit speeds.

Yes, I have a 3870, and am aware that I only get 1-bit speed. In fact, that's why I said:


That means that devices that run in MMC-compatibility mode won't take full advantage of SD cards (like my iPAQ 3870 :-().

:-D


If you get any performance improvements let us know. :)

I'll probably conduct a couple of copy tests to see if I get better performance. If those show that I do, I'll probably use the Backup Utility to back my iPAQ up onto the SD card. Trying that on my 128 MB card was painfully slow -- it tooks hours if I recall correctly. If I get a 5x improvement, it may be worth trying again.

I think backing up to Compact Flash only took 30-45 minutes.

Steve