C program to write 4096 bytes starting at a random 512b sector, with sector offset passed in from the command line. Try it with your 4K sector hard drive (or SSD): non zero offsets will significantly reduce performance. Use only on an empty disk

testWriteAmplification.c

#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>

char buffer[4096];

int main(int argc, char *argv[])
{
    int fd, i, off;
    long bk, byte;

    if (argc<2) {
        off = 0; 
    } else {
        off = atoi(argv[1]);
    }  

    srandom(off);

    fd = open("/dev/sdc", O_RDWR | O_SYNC);

    for (i=0; i<1000; i++) {
        bk = random() % 200000000;
        byte = bk * 4096 + off * 512;
        lseek64(fd, byte, SEEK_SET);
        write(fd, buffer, 4096);
    }  

    close(fd);

    return 0; 
}