Samsung NVMe write issue

[Raf6969]

Hello friends,

 

I am hoping someone can give any suggestions on how to troubleshoot slow write speeds with some Samsung Pro NVMe SSDs, the operating system is CentOS 7 and they are in software raid 1. At first they worked good, what you would expect for 970 pros... 1500MB/s+ write speed., but now after a few months I can only get 300MB/s~ write speed it, nothing on the OS has changed since, just time has gone by. Read speed is still normal, hdparm results in 2700MB/s - 3400MB/s read speed but write speed with any dd /dev/zero command to test results in between 280MB/s to 400MB/s write, no more than that.

I am not sure how to troubleshoot it since it is only write speed that is slow.

[WereCatf]

3 minutes ago, Raf6969 said:

I am not sure how to troubleshoot it since it is only write speed that is slow

Enable discard, ie. TRIM, and then do fstrim /path/to/your/filesystem

[Raf6969]

1 hour ago, WereCatf said:

Enable discard, ie. TRIM, and then do fstrim /path/to/your/filesystem

will fstrim cause any problems with existing data? I tried previously but it said it wasn't a directory or something similar.

[WereCatf]

4 minutes ago, Raf6969 said:

will fstrim cause any problems with existing data? I tried previously but it said it wasn't a directory or something similar.

No, it won't. Also, you need to point it to the mounted filesystem, not the devices in /dev.