FAST SDHC Memory for the EX1

[Stevet]

Sorry for the long rant, but this MAY be extremely helpful is getting us closer to finding a MUCH cheaper memory solution for the EX1. Please read on, I need your help to find the fastest SDHC cards possible

I've been trying to find the fastest SDHC memory possible to use with the AFT PROExpress-7 ExpressCard Reader.
PROExpress-7-Atech Flash Technology

Why this expresscard adaptor. Easy, the SDHC memory cards fit in the adapter AND allows the EX1 memory compartment to close!


OK, I've been having "almost success" with some cards.
Why "almost"? Well, I've been able to capture 20 minutes of 1080 24P without any errors recording and playback. Here's the issue. the success rate is intermittent.

My thought RIGHT NOW is that the majority of the issue is the slow RANDOM ACCESS time from these SDHC cards. Also, the sustained data rate must be kept high for READING and ESPECIALLY WRITING data.

What I'm finding is that several cards I've tested are reading sustained data rates with no issues and maintaining around 18MB/s.
The problem is, the WRITE speed runs from 3.7MB/s to 10.6MB/s (NOTE: this was using the ADATA 8GB SDHC TURBO CLASS 6 card. This card does not perform (at least based on the CLASS 6 designation) as advertised. CLASS 6 states the minimum data rate should not fall below 6MB/S.

Interesting, I tried the SansDisk Ultra II CLASS 4 (min. 4MB transfer rate).
The sustained (MB/s) READ and WRITE speeds were consistant (At least during my tests) and maintained between 16.8 to 17.4 WRITE and 18.19 to 18.21 READ data rate.

Having seen that, I was surprised that the card does occasionally error when used in the EX1. Here's the deal, my thought is it's not JUST the sustained data rate, but how well it writes and reads randomly when asked to.

My conclusion is based on several factors. One, the card works best with no errors when formated and recording without stopping. If I start and stop recording times quickly, an error can occur. Two, I am using memory data rate testing software which evaluates sustained and random data writes and reads.

I was able to test the SxS memory card as a comparison.
Here's the results:

ADATA 8GB SDHC TURBO CLASS 6:

Sustained data rate: Read: 18.64MB/s to 18.69MB/s Write: 3.72MB/s to 10.68MB/s
Random 512K file: Read: 17.96MB/s to 18.69MB/s Write: 2.70MB/s to 3.10MB/s
Random 4K file: Read: 3.57MB/s to 3.91MB/s Write: 0.033MB/s to 0.035MB/s


SanDisk Ultra II SDHC CLASS 4:

Sustained data rate: Read: 18.19MB/s to 18.21MB/s Write: 16.02MB/s to 17.40MB/s
Random 512K file: Read: 17.34MB/s to 17.44MB/s Write: 2.69MB/s to 2.85MB/s
Random 4K file: Read: 3.13MB/s to 3.31MB/s Write: 0.027MB/s to 0.031MB/s


Sony SxS PRO 16GB:

Sustained data rate: Read: 27.53MB/s to 27.57MB/s Write: 20.52MB/s to 20.68MB/s
Random 512K file: Read: 27.51MB/s to 27.54MB/s Write: 7.45MB/s to 8.41MB/s
Random 4K file: Read: 6.45MB/s to 6.46MB/s Write: 0.132MB/s to 0.148MB/s

Just IN (09/17/08):

SanDisk SDHC 16GB Extreme III 30MB/s

Sustained data rate: Read: 19.06MB/s Write: 15.81MB/s
Random 512K file: Read: 18.76MB/s Write: 3.703MB/s
Random 4K file: Read: 3.581MB/s to 6.46MB/s Write: 0.036MB/s

Since all the values were very close to each other, I did not write down a min max range.


As you can see, the SxS random write is between 2 to 3 times faster than the SanDisk Ultra II CLASS 4 card. I'm sure no one is suprised with these results. Also the data is based on one test run. For all I know, and I imagine so, the SxS card within the EX1 performs even faster than these results show.

But, this MAY give us a baseline for finding the fastest SDHC cards possible. As I mentioned earlier, the SanDisk Extreme III 30MB/s card "might" just work. I'm hoping its random read/write is faster along with the claimed data rate improvement.

If anyone can help us out here, it's SanDisk. The results on the Ultra II CLASS 4 SDHC card are better than the CLASS 6 card ADATA.

I won't have the new Extreme card until 2 weeks.

PLEASE download the following Drive Speed Software (PC based, although there maybe a mac version up there too?). It's real easy to run. Just unzip and run the executable. There's no install program, only an executable. Since each tests runs five times, you need to write down the numbers as it runs. This way we can see the min-max data rate range.

Download (Win 2000, XP, VISTA):
http://dl.crystaldew.info/CrystalCPUID

Their Site: http://crystalmark.info/download/index-e.html

PLEASE try your SDHC cards (Transcend (I'm wondering about this card) ect...) and post the results like I did with the above. If you want, take my above results and paste into your message and we can keep a running log of tried SDHC cards.

Also, use only on SDHC cards. PLain old SD cards will not work with the EX1/AFX Express card.


BTW, If none of this crap works good enough in the end. It was worth a shot.
But, SInce I was able to capture over 20 minutes of 1080 24P without an error, it would be stupid not to try to find the fastest memory possible.
We are real close.