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Class 10 vs Class 4 sd cards

Mon Apr 01, 2019 5:16 pm

I bought a 64gb class 10 card from Sandisk, neither raspberry nor boot, I bought a 16g shingling worked. I agree with the classmate of class 10 cards, speed incompatibilities. Then to confirm I bought an ultra class 10 of 128GB of 100MB / s and also happened the same thing. I bought a new Raspberry Pi of 1.4GB of clock and also nothing. Only smaller cards can roll. Now another problem, the cards of lower class after used are giving problems to be formatted. They reduce memory capacity among other issues and can no longer format the Raspberry PI again. Any idea of any colleague?

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Re: Class 10 vs Class 4 sd cards

Mon Apr 01, 2019 6:00 pm

SD-cards of 64GB or more are not FAT32 formatted, so don't work with NOOBS.
The simple solution is to not use NOOBS, but to use ETCHER to image Raspbian directly.
Etcher will overwrite whatever is on the card, and so cards don't have to be formatted at all.
Also please don't attach to several year old threads.

After booting cards will be re-partitioned by Linux, and windows wont see the other partitions, only the small FAT32 boot partition.
If you re-set (re-format) the card by formatting them with the official SD-card association formatter they will return to a single partition again.

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Re: Class 10 vs Class 4 sd cards

Thu Apr 04, 2019 12:26 pm

James33 wrote:
Thu Apr 04, 2019 11:55 am
A Class 4 memory card supports sustained writing at 4MB/s or better; a Class 10 memory card supports sustained writing at 10Mb/s or better. The original Secure Digital card, SD, was accessed by devices by 32-bit memory location, like RAM or other memory types.
I don't much care about the sustained write speeds. Unless the files are very large, writes just go into the disk cache and are instant because its writing to memory.
Much more important is the random read speeds (4K) which are crucial for an operating system. The key metric is IOPS (input/output operations per second) - 4000 IOPS minimum for the A2 class cards.
See the new A1 and A2 class SD cards:
https://havecamerawilltravel.com/photog ... eed-class/
Sandisk from Amazon:
https://www.amazon.co.uk/dp/B073K14CVB/ ... UTF8&psc=1
or high end:
https://www.amazon.co.uk/gp/product/B07 ... A44C592J02
I don't know if the Pi can support anywhere near the claimed "up to 170MB/s" for these cards.

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