On Monday 18 July 2011, Peter Warasin wrote:
$ ./flashbench /dev/sda -f --random --erasesize=$[4*1024*1024] 4MiB 4.38M/s 4.93M/s 3.79M/s 5.04M/s 4.98M/s 4.93M/s 2MiB 4.65M/s 4.95M/s 3.29M/s 2.8M/s 2.84M/s 2.81M/s 1MiB 5.18M/s 4.94M/s 2.04M/s 1.95M/s 1.95M/s 1.95M/s 512KiB 4.35M/s 4.67M/s 1.03M/s 1.02M/s 1.02M/s 998K/s 256KiB 3.33M/s 3.63M/s 613K/s 610K/s 609K/s 611K/s 128KiB 2.34M/s 2.68M/s 298K/s 298K/s 298K/s 298K/s 64KiB 1.36M/s 1.59M/s 147K/s 147K/s 147K/s 147K/s 32KiB 816K/s 1M/s 81.1K/s 81K/s 81K/s 81K/s 16KiB 469K/s 507K/s 40.2K/s 40.3K/s 40.3K/s 40.3K/s
Ok, exactly as expected: the first two columns show erase blocks with the FAT optimization that allow random writes, while the others are only for linear writes and get much slower when used with random access.
Arnd