9 open erase blocks! Looks like a rather nice microSD card, compared to others I've seen.
# BeagleBoard-xM is my only home computer with a built-in MMC device:
root@192:~/flashbench# head /sys/block/mmcblk0/device/* 2>/dev/null | grep -v ^$ ==> /sys/block/mmcblk0/device/block <==
==> /sys/block/mmcblk0/device/cid <==
035344535530344780a0a0dbc100bbc9
==> /sys/block/mmcblk0/device/csd <==
400e00325b5900001d8a7f800a4040b9
==> /sys/block/mmcblk0/device/date <==
11/2011
==> /sys/block/mmcblk0/device/driver <==
==> /sys/block/mmcblk0/device/erase_size <==
512
==> /sys/block/mmcblk0/device/fwrev <==
0x0
==> /sys/block/mmcblk0/device/hwrev <==
0x8
==> /sys/block/mmcblk0/device/manfid <==
0x000003
==> /sys/block/mmcblk0/device/name <==
SU04G
==> /sys/block/mmcblk0/device/oemid <==
0x5344
==> /sys/block/mmcblk0/device/power <==
==> /sys/block/mmcblk0/device/preferred_erase_size <==
4194304
==> /sys/block/mmcblk0/device/scr <==
0235800300000000
==> /sys/block/mmcblk0/device/serial <==
0xa0a0dbc1
==> /sys/block/mmcblk0/device/subsystem <==
==> /sys/block/mmcblk0/device/type <==
SD
==> /sys/block/mmcblk0/device/uevent <==
DRIVER=mmcblk
MMC_TYPE=SD
MMC_NAME=SU04G
MODALIAS=mmc:block
# All further tests done using Transcend USB2.0 reader on my desktop
andrew@bigbox:~/flashbench$ sudo sfdisk -uS -l /dev/sdc
Disk /dev/sdc: 1890 cylinders, 128 heads, 32 sectors/track Units = sectors of 512 bytes, counting from 0
Device Boot Start End #sectors Id System /dev/sdc1 * 8192 7741439 7733248 c W95 FAT32 (LBA) /dev/sdc2 0 - 0 0 Empty /dev/sdc3 0 - 0 0 Empty /dev/sdc4 0 - 0 0 Empty
andrew@bigbox:~/flashbench$ sudo ./flashbench -a /dev/sdc --blocksize=1024 --count=100 align 1073741824 pre 872µs on 921µs post 873µs diff 48.5µs align 536870912 pre 872µs on 973µs post 871µs diff 102µs align 268435456 pre 872µs on 935µs post 872µs diff 63.5µs align 134217728 pre 1ms on 1.04ms post 1ms diff 40.1µs align 67108864 pre 966µs on 1.07ms post 976µs diff 97.7µs align 33554432 pre 1ms on 1.07ms post 1.01ms diff 63.6µs align 16777216 pre 999µs on 1.09ms post 1.01ms diff 86.7µs align 8388608 pre 999µs on 1.03ms post 1ms diff 32.3µs align 4194304 pre 1.03ms on 1.12ms post 1.03ms diff 95.6µs align 2097152 pre 999µs on 1.1ms post 1.03ms diff 88.8µs align 1048576 pre 1.01ms on 1.04ms post 1.01ms diff 34.9µs align 524288 pre 1.01ms on 1.03ms post 1.02ms diff 18.4µs align 262144 pre 1.01ms on 1.02ms post 986µs diff 28.5µs align 131072 pre 1ms on 1.03ms post 1.01ms diff 26.9µs align 65536 pre 1ms on 1.03ms post 1.01ms diff 27.1µs align 32768 pre 985µs on 1.03ms post 1ms diff 32.2µs align 16384 pre 986µs on 982µs post 966µs diff 5.55µs align 8192 pre 1.01ms on 1ms post 1.01ms diff -9139ns align 4096 pre 981µs on 1.03ms post 1.04ms diff 25.9µs align 2048 pre 974µs on 977µs post 973µs diff 3.65µs
## 2MiB erase block ## 8KiB pages? hard to see
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=1 2MiB 13.2M/s 1MiB 13.1M/s 512KiB 12.9M/s 256KiB 12.9M/s 128KiB 12.8M/s 64KiB 12.2M/s 32KiB 12.9M/s 16KiB 13M/s 8KiB 9.61M/s 4KiB 6.5M/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=2 2MiB 13M/s 1MiB 7.34M/s 512KiB 12M/s 256KiB 12.2M/s 128KiB 11.4M/s 64KiB 10.3M/s 32KiB 8.52M/s 16KiB 6.35M/s 8KiB 3.46M/s 4KiB 1.6M/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=3 2MiB 13M/s 1MiB 8.41M/s 512KiB 12.5M/s 256KiB 12.1M/s 128KiB 11.6M/s 64KiB 10.3M/s 32KiB 8.6M/s 16KiB 6.39M/s 8KiB 3.46M/s 4KiB 1.62M/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=9 2MiB 12.8M/s 1MiB 11M/s 512KiB 12.4M/s 256KiB 12.2M/s 128KiB 11.5M/s 64KiB 10.3M/s 32KiB 8.57M/s 16KiB 6.33M/s 8KiB 3.37M/s 4KiB 1.6M/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --open-au-nr=10 2MiB 13M/s 1MiB 6.88M/s 512KiB 2.41M/s 256KiB 1.1M/s 128KiB 531K/s 64KiB 263K/s 32KiB 130K/s 16KiB 64.8K/s 8KiB 302K/s 4KiB 346K/s
# 9 open-au has same performance as 2 open-au.
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --random --open-au-nr=1 2MiB 10.7M/s 1MiB 12.7M/s 512KiB 11.7M/s 256KiB 3.55M/s 128KiB 1.18M/s 64KiB 652K/s 32KiB 310K/s 16KiB 180K/s 8KiB 872K/s 4KiB 1.08M/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --random --open-au-nr=2 2MiB 12.4M/s 1MiB 12.6M/s 512KiB 12.2M/s 256KiB 3.56M/s 128KiB 1.18M/s 64KiB 649K/s 32KiB 310K/s 16KiB 179K/s 8KiB 844K/s 4KiB 982K/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --random --open-au-nr=3 2MiB 12.4M/s 1MiB 12.9M/s 512KiB 12.3M/s 256KiB 3.56M/s 128KiB 1.18M/s 64KiB 652K/s 32KiB 311K/s 16KiB 178K/s 8KiB 869K/s 4KiB 1M/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --random --open-au-nr=9 2MiB 10.4M/s 1MiB 12.6M/s 512KiB 12.1M/s 256KiB 3.54M/s 128KiB 1.18M/s 64KiB 647K/s 32KiB 310K/s 16KiB 180K/s 8KiB 820K/s 4KiB 928K/s
andrew@bigbox:~/flashbench$ sudo ./flashbench /dev/sdc --open-au --erasesize=$[2*1024*1024] --blocksize=$[4*1024] --random --open-au-nr=10 2MiB 11.9M/s 1MiB 6.83M/s 512KiB 2.4M/s 256KiB 1.1M/s 128KiB 531K/s 64KiB 263K/s 32KiB 130K/s 16KiB 64.8K/s 8KiB 929K/s 4KiB 954K/s