Question SSD performance tanks after adding 2nd drive ?

[sportsphotoguy]

Just added a new Crucial P1 500GB NVMe PCIe M.2 SSD to my new Dell G5 15 5505 laptop in the 2nd M2 slot. First I noticed the weird hiccup in performance with this drive - in probably thousands of tests with the ATTO benchmark over the years, I've come to just about always see a steady increase in performance as the transfer size increases - never a bell. So then I tested the original stock SSD, a Samsung P991, and saw the write performance on that one completely tank compared to a pre-upgrade benchmark. The Samsung's poor performance was confirmed using AS-SSD as well (though without a pre-upgrade test for comparison). Any ideas what is going on here?

 

[faalin]

Does the speed return if you only run 1 drive?

If it does then they are probably sharing PCI-e lanes.

 

[sportsphotoguy]

No, write performance bottleneck is still there now - so it must have been something else? I have Dell Support working on this, which has been very prompt to respond if nothing else. Will report back here, but would still appreciate any opinions the community might have to offer.

 

[sportsphotoguy]

The plot thickens...CrystalMark confirms the drop off in sequential writes, but random writes are not so bad. Still, for someone who spends a lot of time copying gigabytes worth of photos to this machine, the sequential performance hit still concerns me somewhat.