Question

I need to setup some test conditions to simulate a filled up disk. I created the following to simply write garbage to the disk:

#!/usr/bin/python

import os
import sys
import mmap

def freespace(p):
    """
    Returns the number of free bytes on the drive that ``p`` is on
    """
    s = os.statvfs(p)
    return s.f_bsize * s.f_bavail 

if __name__ == '__main__':

    drive_path = sys.argv[1]
    output_path = sys.argv[2]

    output_file = open(output_path, 'w')

    while freespace(drive_path) > 0:
        output_file.write("!")
        print freespace(drive_path)
        output_file.flush()

    output_file.close()

As far as I can tell by looking at the return value from freespace, the write method does not write the file to until it is closed, thereby making the while condition invalid.

Is there a way I can write the data directly to the file? Or another solution perhaps?

Answer 1

This is untested but I imagine something along these lines will be the quickest way to fill the disk easily

import sys
import errno

write_str = "!"*1024*1024*5  # 5MB

output_path = sys.argv[1]

with open(output_path, "w") as f:
    while True:
        try:
            f.write(write_str)
            f.flush()
        except IOError as err:
            if err.errno == errno.ENOSPC:
                write_str_len = len(write_str)
                if write_str_len > 1:
                    write_str = write_str[:write_str_len/2]
                else:
                    break
            else:
                raise