On 06/01/2021 16:56, Matwey V. Kornilov wrote:
> Another consideration. Does anybody know any research on what FS is
> the most friendly to SD cards?
I believe that would be FAT32 which is what the firmware is optimised
for but of course not very useful for a root fs. F2FS is a flash
optimised FS.
One thing that I found out is that a lot of SD card vendors explicitly
have an expected start sector on SD cards. Internally SD card flash is
segmented into 4MiB blocks or something like that. Hence most SD cards
formatted so that the standard FAT32 partition starts at block 8192. The
Official Raspian Images respect this too by placing the boot partition
at sector 8192 (you can validate this with `fdisk -l /dev/mmcblk0`).
This could make a difference in performance.
This also may be important because some bootloader images are located before the first partition. For instance, u-boot.img is placed at 768 at beagle bone black. And currently only 655360 bytes are available for this image. It has already raised some booting bugs when u-boot.img didn't fit into this place and overwrote the first partition.
I tried to test this by building an image locally but failed due to some
weird dependency issues. You should be achieve the alignment by changing
the <type> tag in the .kiwi like `<type image="oem"
disk_start_sector="8192">`
I would like to benchmark and compare multiple FS as well as the
difference the alignment could do if I can get it to build.
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Tamara Schmitz
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