The Patriot Hellfire M.2 480GB Review: Phison NVMe Testedby Billy Tallis on February 10, 2017 8:30 AM EST
Our performance consistency test explores the extent to which a drive can reliably sustain performance during a long-duration random write test. Specifications for consumer drives typically list peak performance numbers only attainable in ideal conditions. The performance in a worst-case scenario can be drastically different as over the course of a long test drives can run out of spare area, have to start performing garbage collection, and sometimes even reach power or thermal limits.
In addition to an overall decline in performance, a long test can show patterns in how performance varies on shorter timescales. Some drives will exhibit very little variance in performance from second to second, while others will show massive drops in performance during each garbage collection cycle but otherwise maintain good performance, and others show constantly wide variance. If a drive periodically slows to hard drive levels of performance, it may feel slow to use even if its overall average performance is very high.
To maximally stress the drive's controller and force it to perform garbage collection and wear leveling, this test conducts 4kB random writes with a queue depth of 32. The drive is filled before the start of the test, and the test duration is one hour. Any spare area will be exhausted early in the test and by the end of the hour even the largest drives with the most overprovisioning will have reached a steady state. We use the last 400 seconds of the test to score the drive both on steady-state average writes per second and on its performance divided by the standard deviation.
The Patriot Hellfire maintains a higher average random write speed than the significantly more expensive OCZ RD400 and the older Samsung 950 PRO, but the Plextor M8Pe performs even better, especially when heatsinks are used.
The Patriot Hellfire does not have the very high consistency of the Intel SSD 750 or most of Samsung's SSDs, but the score is not worryingly low. For consumer-oriented products, consistency under sustained write load is generally a lower priority than high burst performance and quick recovery during idle times.
The Patriot Hellfire shows some long-term fluctuations in random write performance, especially when equipped with a heatsink to allow for higher peak performance. With extra overprovisioning, the long-term trend is very stable and the effect of the heatsink is greatly reduced.
On shorter time scales, the Patriot Hellfire is never particularly consistent. Adding a heatsink increases the peak performance but only helps the minimums slightly. Adding extra overprovisioning greatly increases the amount of time spent operating at or near peak performance, but does not entirely eliminate the drops down below 5k IOPS.