simple-sd-card-tester

This is a simple SD/MMC card tester on block level with simple benchmarking features. It is written in shell with the help and use of GNU userland on Linux.

Needs

• sed
• dd (uses oflags=direct, iflags=fullblock)
• md5sum
• tee
• POSIX shell

Usage

   test-sd-card.sh - a simple SD card testing tool, with small benchmarking features

     usage: test-sd-card.sh [opt] [opt] ... [blockdevice]

       opts:
         -B              display output of dd instances    (no)
         -P              page size in Kilo Bytes           (4 MiBi)
         -W              write size in Kilo Bytes          (1 GiBi)
         -f              full write of blockdevice         (no)
                         (page size == write size)
         --keep-data     keep data files                   (no)
         --keep-checksum keep data files                   (no)
         --source        source device                     ($SOURCE)

     hints:
       * Usually you have a simple wrap around in address lanes on bad
         SD/MMC cards. This results in data written at the wrap around
         memory, erasing the beginning of the card.
       * If the MMC/SD card has a better FTL in place, a full write
         is needed as it tracks the written areas of the embedded flash.
         If a quick scan does not discover errors, use -f, if suspicous.

Examples

Test SD card at /dev/sdc parttially, without benchmark output

     sh test-sd-card.sh /dev/sdc

This would write currently 4 MiBi at every 1G of the block device of the SD card. It would detect wrap around errors on cheap SD/MMC cards with or without a stupid FTL (flash transaction layer) A bad flash chip with a good FTL would fool that test.

Test SD card at /dev/sdc partially, with 64 MiBi page size and 1 MiBi write blocks

     sh test-sd-card.sh /dev/sdc -P 65536 -W 1024

Test SD card at /dev/sdc fully, with 64 MiBi pages

     sh test-sd-card.sh /dev/sdc -f -P 65536

This would write the SD card in 64MiBi pages. It would detect FTL and wrap around errors on cheap SD/MMC cards.

Test SD card at /dev/sdc fully, with 64 MiBi pages, and simple benchmarking output

     sh test-sd-card.sh /dev/sdc -f -P 65536 -B

ToDo / Bugs

• -W & -P accept KiBi bytes, but internally everything is done MiBi bytes, so using -W and -P with values less than 1024, would break that script.
• used pipes and checksum files are not cleaned up on error exit/^C/... (not yet, use trap)
• it uses the current directory as datafile and checksum file storage, use mktemp, etc. for tempfiles

License

GPL, see LICENSE file