smr_characterisation.py

#!/usr/bin/env python
# -*- coding: utf-8 vi:noet
# Characterization test for SMR drives

import sys, os, subprocess, time, mmap

if __name__ == "__main__":

	device = sys.argv[1]

	size = int(subprocess.check_output(["blockdev", "--getsize64", device]).decode().rstrip())
	print("{device} has size {size}".format(**locals()))

	fd = os.open(device, os.O_RDWR | os.O_DIRECT)

	buflen = 1<<20

	def pattern_gen():
		buf = mmap.mmap(-1, buflen)
		pos = size - buflen
		while pos > 0:
			yield buf, pos
			pos -= 100 * (1<<20)

	now = time.time()
	last = now
	last_count = 0
	for idx_offset, (buf, offset) in enumerate(pattern_gen()):

		now = time.time()
		if now > last + 1:
			iops = idx_offset - last_count
			print("---")
			print("{} iops".format(iops))
			print("{:.3f} GB written".format(idx_offset * buflen / 1e9))

			last_count = idx_offset
			last = now

		res = os.pwrite(fd, buf, offset)
		if res != buflen:
			break