Mixed and Steady State Workload Performance
80% Read Mixed Workloads
Mixed workloads are particularly taxing. NVMe opens up the path to an SSD's flash by facilitating full-duplex data transfers, allowing the drive to read and write at the same time. SATA is half-duplex, so latency goes up fast when you start mixing reads and writes.
The 950 Pro's excellent sequential performance shines through in our mixed workload at low queue depths. It isn't until a queue depth of eight that Intel's SSD 750s overtake the 512GB 950 Pro in this sequential metric.
Samsung's 512GB 950 Pro impresses with its low queue depth random mixed workload performance. The Intel SSD 750s are faster when they're subjected to 100% random writes. However, when we mix the data, the big 950 Pro has a clear edge. Most enthusiasts will never push enough data to actually see the difference, though. Really, it makes more sense to focus on price and capacity when you're looking at this much performance.
Sequential Mixed Workloads in Steady State
The large drop-off in steady state sequential performance with an increase on the write side is called a bathtub curve. This relates to how mixed reads and writes tax SSD controllers. Some drives handle the duress better than others. Processors with more cores running at higher clock rates tend to fare better than those with mainstream-oriented specs.
Random Writes in Steady State
This is the first time we've been able to show how consistent random write performance correlates with consistent RAID performance. The black line shows a single 512GB 950 Pro. You can see how one drive's deviation doubles in a striped array. The trick is to minimize the differences between highs and lows, since they'll increase as drives are added.
The chart also shows how enabling RAID 0 through Intel's PCH can improve the storage subsystem's performance under heavy loads.
The 950 Pro is a good candidate for client-level RAID 0, though it'd behave even better if we could get an optimized driver from Samsung.