Question Extremely Slow Random Writes on Samsung 990 Pro NVME

[eastpond]

I'm getting some strange behavior from a brand new Samsung 990 Pro drive after installing it. Firmware is up to date, trim enabled and I've let it idle for several hours while completing other tasks hoping it was a write cache issue that would sort itself out. No luck there.

I'm running it with a Sonnet 4x4 PCIe NVME adapter on a Mac Pro 7,1 Sonoma.

Even though it's PCIe 3.0, the sequential speeds are good. Random 4k Reads also good.

But it falls off a cliff with Random Writes.

https://imgur.com/aCXjXxO

I have a Samsung 9100 Pro that's also plugged into the same Sonnet card, and those results are great:

https://imgur.com/tkdElnK

I'm stuck for what to try next.

 

[Lutfij]

Even though it's PCIe 3.0, the sequential speeds are good. Random 4k Reads also good.
IMHO, you're on par with PCIe3.0 speeds.

I'm running it with a Sonnet 4x4 PCIe NVME adapter on a Mac Pro 7,1 Sonoma.
By any chance are you using this adapter;
https://www.sonnettech.com/product/legacyproducts/m2-4x4-pcie-card.html
?
If so, which slot on the motherboard do you have said updater populating?

 

[eastpond]

I'm running it with a Sonnet 4x4 PCIe NVME adapter on a Mac Pro 7,1 Sonoma.
By any chance are you using this adapter;
https://www.sonnettech.com/product/legacyproducts/m2-4x4-pcie-card.html
?
If so, which slot on the motherboard do you have said updater populating?

Close! I'm using this one below which is just the same card without the fan.
https://www.sonnettech.com/product/m2-4x4-pcie-card/overview.html

I've got it on PCIe Bus 5 which should be a x16 lane spot. I'm only currently using two drives for now, but plan on expanding once I've got the kinks worked out.

I've also tried taking out all other PCIe cards except the default USB/Controller, and no luck. I also used the Expansion Slot Utility to assign the card to its own PCIe Pool (2019 Mac Pro has two available PCIe pools).

Just to be sure it's not a Motherboard problem with this slot, I've tried Slot 6 which is also x16.

No luck so far.

 

[Bob.B]

Close! I'm using this one below which is just the same card without the fan.
https://www.sonnettech.com/product/m2-4x4-pcie-card/overview.html

I've got it on PCIe Bus 5 which should be a x16 lane spot. I'm only currently using two drives for now, but plan on expanding once I've got the kinks worked out.

I've also tried taking out all other PCIe cards except the default USB/Controller, and no luck. I also used the Expansion Slot Utility to assign the card to its own PCIe Pool (2019 Mac Pro has two available PCIe pools).

Just to be sure it's not a Motherboard problem with this slot, I've tried Slot 6 which is also x16.

No luck so far.

Tried different slots on the adapter?

 

[eastpond]

Tried different slots on the adapter, also got a second drive drive to rule out it being defective. Same result.

I also tried the drive on Catalina just out of curiousity. Kind of a stretch but I've heard Apple changed some things with SSD's on Monterey. Side note - the Random Reads 4k QD1 came in at 84-85 MB/sec, almost 10% faster than Sonoma. (!)

The NVME adapter is now the biggest suspect, so I'll swap that out for a different one and report back.

 

[eastpond]

Solved this. The problem is Amorphous DiskMark.

ATTO Disk Benchmark is measuring everything normally.

Also, when installing MacOS and running it directly off the 990 Pro, Amorphous random writes jump back up to expected levels. So there's something about Amorphous DiskMark that doesn't gel with an external 990pro.