53 replies to this topic

[Zeno Arrow]

You get what you pay for. Cheap cards are slow no matter what "class" they claim to be. I have three 16GB cards (one Transcend and two Adata) that all claim to be class 6, but none of them read or write more than 4.5MB/s.

I thought the whole thing with the different classes was about the minimum speed the manufacturers promised the card would offer. Take a look at this SanDisk card for example:
http://tinyurl.com/derv2d
Shown as a Class 2 card (by the looks of the label) but offers 15MB/sec Read/Write speeds.

I'm hoping we will see 64GB soon, 128GB in my Pandora makes me laugh

I think that someone will have to work around the specs to pull this off, kind of like they did with the standard SD format that topped out at 2gb. I know Transend put out a 4gb regular SD card. Someday we'll get there. The crazy thing will be if SDXC is doable through a driver update. We could end up having 4tb in our Pandora's in a few years.

Isn't SDHC good for 2TB?

There is a chance, and bear in mind I'm using guesswork here, that SD cards above 32GB will drop the 'HC' suffix and use the 'XC' suffix instead. After all, why did the original 'SD' label get dropped in favour of 'SDHC'? Increased media size + increased transfer speeds (as far as I can work out). What I'm trying to say is, don't be surprised if SDHC>32GB == SDXC, especially as the formats are controlled by the same group (http://www.sdcard.org/home).

Edited by Zeno Arrow, 03 February 2009 - 02:01 AM.

[White Flame]

Zeno: Where does it say Class 2 anywhere?

[Zeno Arrow]

Zeno: Where does it say Class 2 anywhere?

Have a look on the label of the SD card. IIRC the number in the almost complete circle indicates the class number.

EDIT: Got something to prove what I've been saying. First the label thing:



The meaning behind the class thing:

The SD Association has established a new specification rating for the minimum data transfer for standard and high-capacity cards, as well as both types of host products. With the new Speed Class specifications, the host product can check the fragmented state in the card and calculate the write speed in each part of the card. The host can then determine where to write the data according to its speed requirement. The three SDHC speed classes - Class 2, Class 4 and Class 6 - transfer data at least 2, 4 and 6MB per second.

Source for both: http://www.sdcard.or...pers/tech/sdhc/

Edited by Zeno Arrow, 03 February 2009 - 02:11 AM.

[Chip]

I thought the whole thing with the different classes was about the minimum speed the manufacturers promised the card would offer. Take a look at this SanDisk card for example:
http://tinyurl.com/derv2d
Shown as a Class 2 card (by the looks of the label) but offers 15MB/sec Read/Write speeds.

Yes, and I'm sure that Sandisk card cost quite a bit more than the $30ish 16GB cards I have. As Zeno pointed out, the class is supposed to indicate the minimum MB/s rate the card should provide. I have three class 6 cards from two different manufacturers that don't even meet the minimum. Like I said, you get what you pay for. A good class 4 card from Sandisk or Panasonic will likely outperform any cheap card no matter what it says on the label.

[Zeno Arrow]

I have three class 6 cards from two different manufacturers that don't even meet the minimum.

Chip, surely it's possible that the speed bottleneck isn't caused by the cards themselves but by the device using the cards (badly designed card reader or something of that nature)?

Edited by Zeno Arrow, 03 February 2009 - 02:38 AM.

[White Flame]

Zeno: ah, my mind just skipped over that as being a CE or similar logo for some reason

[Zeno Arrow]

Zeno: ah, my mind just skipped over that as being a CE or similar logo for some reason

No worries White Flame, I didn't know anything about SD card classes until I started visiting these forums!

[Pleng]

From mymemory.co.uk...........that included postage and packing by the way........if they do get cheaper, it won't be by much.

Yes it will.

[GuSec]

You're talking about minimum speeds but have you missed that this does only imply under optimal conditions? This includes factors such as operating system, file system, card reader, card reader driver, fragmentation and card age. Also it can differ from card to card, even in the very same brand and class.