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Old 08-21-2014, 11:04 PM   #9
DNSB
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Posts: 46,445
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Join Date: Jul 2010
Location: Vancouver
Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos
Quote:
Originally Posted by hawhill View Post
Does a Kobo actually work with 64GB cards (thus being SDXC, not SDHC)?

As for Class 4 being faster than Class 10 - I think that would be pure luck. SD cards differ so much, even within the same series. Performance will also depend on the interface, filesystem, driver code and much more. It only makes limited sense to check from a different unit.
I was checking the cards on a single system and the results were pretty consistent over multiple cards. Whether I tested using the Ricoh interface SD card slot or a USB uSD card adapter, the cards that had good small block performance were consistently better than the cards that had poor small block performace.

It had to be admitted that the performance item I was most interested in was not one that most producers of high capacity SD storage cards optimized for, I could see why some of them had very poor performance. However for my uses, the small block performance was a fairly critical measurement and having a good small block read/write performance made a noticeable difference.

I do have some difficulty understanding your belief that a card that performed poorly for small block read/writes in my test setup was going to suddenly perform well in another system. The results in the performance database were pretty consistent. Slugs were slugs regardless of what system they were tested on and a Class 10 card may have blown a Class 4 card out the water for sequential and large block performance but in small block performance, the 4 Class 4 Sandisk cards I tested were one (expletive deleted) of a lot faster than any of the Class 10 cards I tested.

BTW, what got me started on this finding a thread in the XDA Developers conference http://forum.xda-developers.com/show....php?t=1005633. You can also check the GoogleDocs database of the results at https://docs.google.com/spreadsheet/...lRDJQTEE#gid=0

Regards,
David

Last edited by DNSB; 08-21-2014 at 11:16 PM.
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