I think this is a good moment to repost my SSD testing I did some weeks ago ...
In the below picture you see 3 benchmarks for each type of storage you can use in a console except Intel Optane. The tests were performed on my own PC. While the sizes of the mediums differ it will give you still an idea what would be a possible realistic speed estimation.
I only talk about reading operations!
NVMe = Samsung 970 EVO 500GB (4x PCIe Gen3)
SSD = SanDisk Ultra 2TB (SATA3)
HDD = Seagate Barracuda 3TB 7200rpm (SATA3)
If someone is not familiar with this kind of benchmark I now do some explaining what the 4 tests are about
- The first test is a sequential read of 1GB of data with 32 I/O queues by 1 thread (not a valid use case for streaming data to a game, but initial loading)
- The second test is a random reads of 4KB data objects from a 1GB data file with 8 I/O queues done by 8 threads (not likely in a console because of the 8 threads)
- The third test is random reads of 4KB data objects from a 1GB data file with 32 I/O queues done by 1 thread (a typical console use case)
- The fourth test is random reads of 4KB data objects from a 1GB data file with 1 I/O queue done by 1 thread (a worst case scenario)
Analysis:
- A single non-RAID HDD is 50 times worse than any decent SATA3 SSD in random access data read for everything other than sequential read which is not your typical in game streaming use case. So any SSD will be already a huge jump in streaming-to-game capabilities even not optimized! And that is just the worst case scenario. test pattern 3 looks even better where we see 100 times the performance. I repeat: 100 times the performance on the most common access pattern you will find on any system.
- test pattern 1 is showing a 6.4 times increase in speed in favor for the NVMe. The open question is how often you will see that pattern with your games other than initial loading or copying/moving data from drive a to drive b ...
- In test pattern 2 you see a difference by still 4.35 times but I ask if this a valid use case for consoles because you run 8 dedicated threads while you have to maintain your frame rate. Maybe someone actually have deeper knowledge there can shed some led on it....
- In test pattern 3 the NVMe advantage is reduced to a merely 37% on a pattern which is normally your bread and butter access pattern on a PC and maybe on a console too.
- In test pattern 4 which is the worst case scenario my NVMe is just 22.5% better than a SATA3 SSD.
Conclusion:
I am aware that a real world access pattern would be a mix of those tested access patterns but the differences in speed between PC SSDs is not as high if you leave the roam of best case scenarios. But there is also a high chance that a next gen console game optimized for SSD speeds would actually target nearer to the worst case than to the best case to be able to be on-premise almost 100%.
TL;DR
The jump between HDD and SSD is a huge generational leap. The differences in SSD speeds are not as high as many expect them to be here (so far).