Wear leveling

Memory Cards SD | microSD | CFast | CFexpress | CompactFlash
1

Hi,

I have read an older post that wear leveling is included in all falsh memories (http://forums.sandisk.com/t5/Mobile-memory-professional-cards/looking-for-an-micro-SD-card-in-industrial-use-with-high/m-p/300041/highlight/true#M2699), but why is wear leveling only mention in Extreme Pro ( http://www.sandisk.com/products/memory-cards/sd/extremepro-sdxc-sdhc-uhs-1-95mbs/?capacity=8GB)?. Does it exists different types of wear leveling? I am looking for 8GB microSD cards offer high endurance for industrial use. Does Extreme Pro have longer life time than for example http://www.sandisk.com/products/memory-cards/microsd/ultra-class10-with-adapter/?capacity=16GB?

Thanks

Jonas

1 Like
2

:smiley:   Hi Jonas,

Dear member of SanDisk Community, welcome.

Friend, you investigated it which is in the Forum, the next step, to get a very specific answer is:

Contact with SanDisk Technical Support: http://www.sandisk.com/about-sandisk/contact-us/

Regards, Alfred.                                                                                               (Google translated)

3

Extreme Pro I think costs more and the reason why it has more features. I’m sure the differences are not that huge.

4

I was using SDHC cards on rPi, and I am tired of burning cards every 6 months. So, I was advised to buy MMC, but I wanted to be sure they are better than SD. And I found this page.

https://web.archive.org/web/20140805113601/http://www.toshiba.com/taec/Catalog/Line.do?familyid=7&lineid=900195
states:
e-MMC products integrates NAND flash memory and a controller chip in a single package to perform error corrections, wear leveling and bad-block
This means, all eMMC cards include Wear Leveling.

So, in emergency, I have bought an eMMC card plus the micro SD adapter on Amazon. Now, I am still looking for wear leveling in SD cards. For now, I have found various contradictory peaces of information. For SD and SDHC, each manufacturer was free to do any mess; it’s said (but I have not found any proof yet) that SDXC implies WL.

This item states it can do WL:
Delkin Devices 32 GB MicroSDHC 660X UHS-I U3 Memory Card
https://www.amazon.co.uk/gp/product/B00NQX1F6G
(SDHC UHS-1 U3)

https://www.sandisk.fr/oem-design/industrial/industrial-cards
Sandisk Industrial are given for 192TB written …

Out of those OEM-industrial cards (which are not supported by the official chat room), using any standard end user Sandisk card ( https://www.sandisk.fr/home/memory-cards ) in an rPi breaks the waranty. Still, for booting an rPi, they recommend the High Endurance stream (which is also called video surveillance https://www.sandisk.fr/home/memory-cards/microsd-cards/high-endurance-microsd ). Both are SDXC white-white; but the industrial has the word industrial written on it.

I was said that eMMC probably includes a better WL algorythm than any micro SD card. I can’t proof check it.

Here is what I have been said by the Sandisk support chat:

  • all Sandisk cards do WL; but knowing which WL algorythm is used is an industrial secret. Ultra cards do it, even if it’s not mentionned on the product page (it’s officially written on the Extreme page).
  • here is the complete list of end-user items https://www.sandisk.fr/home/memory-cards  ; they all should include WL, and are all supported by the live chat
  • the OEM cards are not supported by the live chat; in example the Industrial range: https://www.sandisk.fr/oem-design/industrial/industrial-cards . For OEM cards, support should be seeked at the reseller.
  • any end-user card inserted in an rPi looses it’s waranty
  • when you have an rPi, and want to insert some stuff in the SD hole, it’s recommended to choose a High Endurance model (also called video-surveillance) https://www.sandisk.fr/home/memory-cards/microsd-cards/high-endurance-microsd . They are very similar to industrial cards, except they don’t have the INDUSTRIAL word.
5

all modern flash devices have wear leveling. The cards you have been using however are not designed to the type of work load a pi will put on the card. sandisk supports recommendation of the high endurance cards is correct if you are looking at retail lines of cards. you could also use industrial cards as well but any support would be though the distributor where you purchased the card not sandisk retail support.