Messages in this thread | | | From | Lutz Vieweg <> | Subject | Re: Improving SD/SDHC/SDXC write performance by using a discard/TRIM like operation | Date | Mon, 04 Jun 2012 20:49:22 +0200 |
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I just found another credible reference claiming existence of an "erase" command for SD cards: The "SD Card Specification Simplified Version of: Part E1" (see: http://www.sandisk.com/Assets/File/OEM/Manuals/SD_SDIO_specsv1.pdf ) states:
> ERASE_WR_BLK_START Sets the address of the first write block to be Index address erased. > ERASE_WR_BLK_END Sets the address of the last write block of the address continuous range to be erased.
Since these are "SD bus commands", I wonder whether they are easily accessible behind usual USB card reader hardware... but the mentioned "formatter" tool seems to be able to do so.
Regards,
Lutz Vieweg
On 06/04/2012 08:27 PM, Lutz Vieweg wrote: > When I read reports from (non-expert) users who claimed that they were able > to restore the initial write performance of their SDXC cards by using a "special > formatter tool" (while normal "formatting" did not improve performance), > I was very sceptical, as I also had read that there is no way to discard/TRIM > blocks on SD/SDHC/SDXC cards. > > But then I noticed that this "special formatter" tool was actually offered (for free) > by the SD Association: > https://www.sdcard.org/downloads/formatter_3/ > ... and its documentation clearly states that this tool is capable of using > "flash erase" operations on SD cards, which are said to be different from > ordinary "overwrites", see > https://www.sdcard.org/downloads/formatter_3/SDFormatter_3.1e.pdf > pages 7 ("Format type Erase" vs. "Format type Overwrite") and the screen shot on page 9. > > Now I wonder: Is there really such a thing as a command to erase NAND flashes > in SD cards like there is for SSDs? If so, it would certainly be a good thing > to support it with Linux block discard... > > Regards, > > Lutz Vieweg >
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