On Monday 18 July 2011, Peter Warasin wrote:
fdisk -ul /dev/sda
Disk /dev/sda: 3965 MB, 3965190144 bytes 128 heads, 32 sectors/track, 1890 cylinders, total 7744512 sectors Units = sectors of 1 * 512 = 512 bytes Disk identifier: 0x00000000
Again a multiple of 1.5 MB, just like your other Sandisk card.
Device Boot Start End Blocks Id System /dev/sda1 1 614399 307199+ 83 Linux /dev/sda2 614400 819199 102400 83 Linux /dev/sda3 819200 1851391 516096 82 Linux swap / Solaris /dev/sda4 1851392 7364607 2756608 83 Linux
$ ./flashbench -a /dev/sda3 --count=100 align 134217728 pre 2.62ms on 2.61ms post 2.57ms diff 20.6µs align 67108864 pre 2.61ms on 2.61ms post 2.57ms diff 20.3µs align 33554432 pre 2.75ms on 2.78ms post 2.59ms diff 113µs align 16777216 pre 2.54ms on 2.6ms post 2.47ms diff 91.4µs align 8388608 pre 2.61ms on 2.6ms post 2.41ms diff 93.6µs align 4194304 pre 2.61ms on 2.61ms post 2.6ms diff -1301ns align 2097152 pre 2.61ms on 2.61ms post 2.61ms diff -115ns align 1048576 pre 2.61ms on 2.61ms post 2.61ms diff 5.14µs align 524288 pre 2.61ms on 2.61ms post 2.61ms diff 2.06µs align 262144 pre 2.61ms on 2.61ms post 2.61ms diff 4.23µs align 131072 pre 2.61ms on 2.61ms post 2.61ms diff 3.11µs align 65536 pre 2.62ms on 2.62ms post 2.62ms diff 945ns align 32768 pre 2.68ms on 2.67ms post 2.7ms diff -18986n
-> 8MiB (??)
That would be very unusual for a small card. Typical erase block sizes for 4GB cards are at most 4 MB, others in the list are 2 MB, 1.5 MB or 3 MB.
./flashbench /dev/sda3 --open-au-nr=1 -O --blocksize=2048 --erasesize=$[1024*1024*1] 1MiB 6.96M/s 512KiB 7.67M/s 256KiB 7.01M/s 128KiB 7.76M/s 64KiB 10M/s 32KiB 7.65M/s 16KiB 3.07M/s 8KiB 2.94M/s 4KiB 1.71M/s 2KiB 997K/s
$ ./flashbench /dev/sda3 --open-au-nr=1 -O --blocksize=2048 --erasesize=$[1024*1024*4] 4MiB 7.26M/s 2MiB 7.14M/s 1MiB 7.67M/s 512KiB 7.45M/s 256KiB 6.85M/s 128KiB 7.88M/s 64KiB 10M/s 32KiB 8.38M/s 16KiB 3.02M/s 8KiB 2.86M/s 4KiB 1.74M/s 2KiB 956K/s
-> ok, so it's more likely 4MiB ?
If it was 4 MB, the numbers for the 1 MB test would likely be worse. I'd still guess 1.5 MB.
$ ./flashbench /dev/sda3 --open-au-nr=7 -O --blocksize=2048 --erasesize=$[1024*1024*4] 4MiB 3.75M/s 2MiB 2.72M/s 1MiB 1.43M/s 512KiB 1.23M/s 256KiB 1.19M/s 128KiB 1.26M/s 64KiB 1.78M/s 32KiB 1.65M/s 16KiB 1.41M/s 8KiB 1.31M/s 4KiB 1.11M/s 2KiB 689K/s
$ ./flashbench /dev/sda3 --open-au-nr=9 -O --blocksize=2048 --erasesize=$[1024*1024*4]
4MiB 3.16M/s 2MiB 3.02M/s 1MiB 1.26M/s 512KiB 996K/s 256KiB 971K/s ^C
-> ok, would say, it's 7 blocks
Yes, either 7 or 8 probably, but not 9.
./flashbench /dev/sda3 --open-au-nr=7 -O --blocksize=2048 --erasesize=$[1024*1024*4] --random 4MiB 3.52M/s 2MiB 2.93M/s 1MiB 1.38M/s 512KiB 843K/s 256KiB 474K/s ^C
./flashbench /dev/sda3 --open-au-nr=1 -O --blocksize=2048 --erasesize=$[1024*1024*4] --random 4MiB 7.25M/s 2MiB 7.38M/s 1MiB 7.67M/s 512KiB 2.44M/s 256KiB 1.13M/s 128KiB 2.06M/s 64KiB 1.2M/s 32KiB 597K/s 16KiB 301K/s 8KiB 1.32M/s 4KiB 801K/s 2KiB 439K/s
-> ok, would say this card is not for random access
Yes, possibly, but you should test again with 1.5 MB erase blocks before discarding this.
Arnd