microSDHC class 4 or class 6?

Andrew Burgess elist at cichlid.com
Sat Jul 19 17:17:22 CEST 2008

> On, 2008-07-18 kello 15:14 -0500, Hans L kirjoitti:

>> On Fri, Jul 18, 2008 at 2:26 PM, Andrew Burgess <elist at cichlid.com> wrote:

>> Can the Freerunner make use of the class 6 speed?
>> If not I'll go for the max size.

> According to http://en.wikipedia.org/wiki/Secure_Digital_card#SDHC
> Class 4 supports a minimum write speed of 4MB/s, and 6MB/s for class 6.

Correct and sorry for not defining my terms

> Not sure how fast the Freerunner is capable of writing though.

That's my real question

> According to raster the glamo (which is also the SD card
> controller) bus speed is "7.3m/s" (I presume from context he
> means megabytes). This with the cpu doing nothing else
> besides transferring data to or from the card; thus in
> practice I don't think the class 4/6 distinction is going to
> matter much on the FR. I would go for the size (and did,
> with my 8 GB

I saw a post (here?) about the performance of different
filesystems and I recall seeing flash performance numbers of 9MB/s.
Maybe that was read speed but 9 > 7...

> But, I haven't experimented with the different classes, so grains of salt

OK, I'll volunteer.

I just ordered a 4GB class 6 and an 8GB class 4 from Newegg, both
Transcend brand. I'll post results next week.

Also, there were some wait state tweaks posted on the kernel
list to speedup glamo access. They were /sys controllable so
I'll throw them into the mix.

My little contribution :-)

Andrew Burgess

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