The Toshiba TR200 3D NAND SSD Review: One Step Forward, One Step Back

Power Management

Real-world client storage workloads leave SSDs idle most of the time, so the active power measurements presented earlier in this review only account for a small part of what determines a drive's suitability for battery-powered use. Especially under light use, the power efficiency of a SSD is determined mostly be how well it can save power when idle.

SATA SSDs are tested with SATA link power management disabled to measure their active idle power draw, and with it enabled for the deeper idle power consumption score and the idle wake-up latency test. Our testbed, like any ordinary desktop system, cannot trigger the deepest DevSleep idle state.

Idle power management for NVMe SSDs is far more complicated than for SATA SSDs. NVMe SSDs can support several different idle power states, and through the Autonomous Power State Transition (APST) feature the operating system can set a drive's policy for when to drop down to a lower power state. There is typically a tradeoff in that lower-power states take longer to enter and wake up from, so the choice about what power states to use may differ for desktop and notebooks.

We report two idle power measurements. Active idle is representative of a typical desktop, where none of the advanced PCIe link or NVMe power saving features are enabled and the drive is immediately ready to process new commands. The idle power consumption metric is measured with PCIe Active State Power Management L1.2 state enabled and NVMe APST enabled.

Drives using the Phison S10 controller have usually been the clear winners in the active idle power consumption test but not quite competitive when the slumber state us activated. The S11 controller used by the TR200 seems to be a little less effective at saving power with slumber state disabled, but when it's enabled they set a new record and are just barely within the resolution of our meter.

The exceptional idle power management of the TR200 comes at the cost of a fairly high wake-up latency, about 2.4 milliseconds, more than twenty times as long as the TR150 takes to wake up.