Quote:
Originally Posted by DNSB
Very often the Class 10 cards have done optimization for speed with large data blocks (writing 10MB on my digital camera). They seem to sacrifice small block speeds to obtain the better large block speeds.
I'm one of the people mentioning the lower class cards as being better in some circumstances. This originally came out of a Nook related discussion where some people found their Nook booted from an SD card performed well and others complaining this made their Nook run slower than molasses running uphill in Tuktoyaktuk in January.
I've attached 3 images from various Crystal DiskMark tests I ran on microSD cards (Lexar Class 10, Patriot Class 10 and a SanDisk Class 4 all 8GB) using the internal card reader on my laptop. In my digital and video cameras, the two Class 10 cards worked well. In my Glo, they made it noticeably slower. I suspect this is due to the small block writes where the Class 4 SanDisk was 65 to 171 times faster. The similarity of the sequential read speeds is, I suspect, a limitation of the Ricoh chip used for the card reader.
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Not so much an issue with Class 10 cards as it is with the manufacturers themselves. If you test a Patriot Class 4, I reckon you'd get the same abysmal random 4K writes as the Patriot Class 10. Manufacturers with decent random 4K are SanDisk and Samsung and that's pretty much regardless of capacity and Class.