3 ms·

That's very interesting and explains a number of things. 4MB writes seems pretty high though as a minimum write block size, I've googled but can't find details

by jng 6y ago

That's very interesting and explains a number of things. 4MB writes seems pretty high though as a minimum write block size, I've googled but can't find details among the sea of pages trying to sell me SD cards, won't you by chance have a reference? Thanks!

numpad0 6y ago
Google search for "microsd erase block size"[0] From a forum post in raspberrypi.org[1]: > My 16 GB SanDisk Extreme Pro 45 MB/s UHS 1 card reports an erase block size of 4 MB. > My 8 GB Transcend SDHC Class 6 150x card reports an erase block size of 4 MB. > My 2 GB Transcend SD 150x card reports an erase block size of 8 kB. . From another post from StackExchange.com[2]: > the data cannot be overwritten without being erased first and an erase block is the smallest unit that a NAND flash storage can erase. The erase block size is typically between 128 kB and 2 MB. . According to a Micron Technical Note from 2006[3]: > The NAND Flash device discussed in this technical note is based on a 2Gb asynchronous SLC device and its parameters (unless otherwise noted). > The NAND Flash array is grouped into a series of blocks, which are the smallest erasable entities in a NAND Flash device. > A NAND Flash block is 128KB. Erasing a block sets all bits to 1 (and all bytes to FFh). Programming is necessary to change erased bits from 1 to 0. The smallest entity that can be programmed is a byte. (Note: 2 gigabits = 256 MB) . In a more modern TLC 3D NAND chip from 2016[4]: > Block Size 27,888K bytes or 27.888MB --- [0]: https://www.google.com/search?q=microsd+erase+block+size https://www.google.com/search?q=microsd+erase+block+size [1]: https://www.raspberrypi.org/forums/viewtopic.php?t=11258 https://www.raspberrypi.org/forums/viewtopic.php?t=11258 [2]: https://raspberrypi.stackexchange.com/questions/32884/ https://raspberrypi.stackexchange.com/questions/32884/ [3]: https://www.micron.com/-/media/client/global/documents/products/technical-note/nand-flash/tn2961_wear_leveling_in_nand.pdf https://www.micron.com/-/media/client/global/documents/produ... [4]: https://www.micron.com/-/media/client/global/documents/products/product-flyer/3d_nand_flyer.pdf?la=en https://www.micron.com/-/media/client/global/documents/produ...
- jng 6y ago
  Thank you, very useful information. Makes complete sense for a media type initially designed to power cameras and audio and video recorders.
deleted 6y ago
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by jng 6y ago

numpad0 6y ago

Google search for "microsd erase block size"[0] From a forum post in raspberrypi.org[1]: > My 16 GB SanDisk Extreme Pro 45 MB/s UHS 1 card reports an erase block size of 4 MB. > My 8 GB Transcend SDHC Class 6 150x card reports an erase block size of 4 MB. > My 2 GB Transcend SD 150x card reports an erase block size of 8 kB. . From another post from StackExchange.com[2]: > the data cannot be overwritten without being erased first and an erase block is the smallest unit that a NAND flash storage can erase. The erase block size is typically between 128 kB and 2 MB. . According to a Micron Technical Note from 2006[3]: > The NAND Flash device discussed in this technical note is based on a 2Gb asynchronous SLC device and its parameters (unless otherwise noted). > The NAND Flash array is grouped into a series of blocks, which are the smallest erasable entities in a NAND Flash device. > A NAND Flash block is 128KB. Erasing a block sets all bits to 1 (and all bytes to FFh). Programming is necessary to change erased bits from 1 to 0. The smallest entity that can be programmed is a byte. (Note: 2 gigabits = 256 MB) . In a more modern TLC 3D NAND chip from 2016[4]: > Block Size 27,888K bytes or 27.888MB --- [0]: https://www.google.com/search?q=microsd+erase+block+size https://www.google.com/search?q=microsd+erase+block+size [1]: https://www.raspberrypi.org/forums/viewtopic.php?t=11258 https://www.raspberrypi.org/forums/viewtopic.php?t=11258 [2]: https://raspberrypi.stackexchange.com/questions/32884/ https://raspberrypi.stackexchange.com/questions/32884/ [3]: https://www.micron.com/-/media/client/global/documents/products/technical-note/nand-flash/tn2961_wear_leveling_in_nand.pdf https://www.micron.com/-/media/client/global/documents/produ... [4]: https://www.micron.com/-/media/client/global/documents/products/product-flyer/3d_nand_flyer.pdf?la=en https://www.micron.com/-/media/client/global/documents/produ...

jng 6y ago
Thank you, very useful information. Makes complete sense for a media type initially designed to power cameras and audio and video recorders.

deleted 6y ago

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