.. This work is licensed under a Creative Commons Attribution 4.0 International License.
.. http://creativecommons.org/licenses/by/4.0
.. (c) 2017 ZTE Corp.


***********
Storage QPI
***********

The storage QPI gives user an overall score for storage performance.

The measurement is done by `StorPerf`_.

.. _StorPerf: https://wiki.opnfv.org/display/storperf

Baseline
========

Baseline is established by testing with a set of work loads:

- `Queue depth`_ (1, 2, 8)
- `Block size`_ (2KB, 8KB, 16KB)
- `Read write`_
  - sequential read
  - sequential write
  - random read
  - random write
  - random mixed read write 70/30

.. _Queue depth: http://fio.readthedocs.io/en/latest/fio_man.html#cmdoption-arg-iodepth
.. _Block size: http://fio.readthedocs.io/en/latest/fio_man.html#cmdoption-arg-blocksize
.. _Read write: http://fio.readthedocs.io/en/latest/fio_man.html#cmdoption-arg-readwrite

Metrics
=======

- Throughput: data transfer rate
- IOPS: I/O operations per second
- Latency: response time

Workload Scores
===============

For each test run, if an equivalent work load in baseline is available, a score will be calculated by comparing the
result to baseline.

Section Scores
==============

+-----------------+--------------------------------------------------------+-----------------------------------------+
| Section         | Detail                                                 | Indication                              |
+=================+========================================================+=========================================+
| IOPS            | Read write I/O Operation per second under steady state | Important for frequent storage access   |
|                 | Workloads : random read/write                          | such as event sinks                     |
+-----------------+--------------------------------------------------------+-----------------------------------------+
| Throughput      | Read write data transfer rate under steady state       | Important for high throughput services  |
|                 | Workloads: sequential read/write, block size 16KB      | such as video server                    |
+-----------------+--------------------------------------------------------+-----------------------------------------+
| Latency         | Average response latency under steady state            | Important for real time applications    |
|                 | Workloads: all                                         |                                         |
+-----------------+--------------------------------------------------------+-----------------------------------------+

Section score is the `geometric mean <https://en.wikipedia.org/wiki/Geometric_mean>`_ of all
workload score.

Storage QPI
===========

Storage QPI is the `weighted arithmetic mean <https://en.wikipedia.org/wiki/Weighted_arithmetic_mean>`_ of all section
scores.