[SOLVED] Low sequential write performance on 1TB 860 QVO

[acerninetes]

I ran UserBenchmark and the sequential write speed of my SSD came out as way below expectations (9th percentile). I ran Samsung Magician's benchmark and got these results:

The advertised sequential read and write speeds are up to 500MB/S, so the read speed seems fairly good but the write speed is way below my expectations.

It's connected to a B450 Tomahawk Max motherboard with a 6Gb/s SATA cable.

Any idea why the write speed is so low and how I could fix this? I tried swapping SATA cables to no avail.

 

[USAFRet]

1. Don't use userbenchmark.
2. Do you have RAPID mode turned on?
3. Is this the OS drive?

 

[acerninetes]

1. Don't use userbenchmark.
2. Do you have RAPID mode turned on?
3. Is this the OS drive?

I don't have RAPID on as the consensus seemed to be against using it. This is the OS drive.

 

[USAFRet]

Actually, all your numbers are not great.
My 850 EVO 500GB C drive.

The other Samsung's in this system have similar numbers.

 

[Maxxify]

1TB QVO's base QLC speed is 80 MB/s, just FYI. You're very clearly in QLC for that benchmark. Only within the SLC cache will you hit marketed numbers. Make sure write caching is enabled though.

 

[USAFRet]

oooo...didn't even notice it was a QVO.

 

[Maxxify]

Yeah, his low IOPS also indicates he's purely in direct-to-QLC mode (36K/21K matches precisely). Most benchmarks will fit inside SLC so there might still be something wrong with the drive anyway (it's not emptying SLC etc) but those speeds are not abnormal for QLC.

 

[acerninetes]

Yeah, his low IOPS also indicates he's purely in direct-to-QLC mode (36K/21K matches precisely). Most benchmarks will fit inside SLC so there might still be something wrong with the drive anyway (it's not emptying SLC etc) but those speeds are not abnormal for QLC.

Thank you both for the feedback - when downloading the write speed registered as around 500MB/s, presumably due to the smaller load. Since none of the health scans found any issue I will assume everything is as it should be. Thanks again

 

[Maxxify]

Yes, it will only have peak speeds within the SLC cache which is 6GB + 36GB * fill rate of the drive, e.g. 42GB at 0% usage and 6GB at 100% usage. This SLC cache will empty when the drive is idle. FYI the 860 QVO is best at 2TB as it has the largest relative SLC cache size and can also interleave (the MJX controller is 8-channel, requiring 16 x 128GiB dies).

 

[popatim]

I bet they are in the wrong cache mode in windows.