Guys,
I am really hoping you can help me out with this issue I having. I have a Dell C2100 with an H200 and 6gbps SAS Backplane. I have 5x 2TB, 1x 5TB, 3x 3TB, 2x 73GB (SAS that are currently removed from the array for troubleshooting). The 2TB are 3gbps, and the rest are 6gbps.
After a transfer is started to the server, the write speeds go WAY down after anywhere from 5-50minutes. The dirty cache (grep - i dirty /proc/meminfo) remains full, so I know that the network transfer speed/SMB are working correctly. It just looks like the dumping from dirty cache (memory) to disk becomes slow. I see no errors in the server's SEL or syslog regarding the issue.
I have tried:
Flashing the H200 to P20, P19, Dell 6Gbps FW, and stock. - Same issue each time
Starting a Parity Check immediately after the speed drops - Once dirty cache is empty, all drives go to 100MB/s.
This tells me its likely not the controller/overheating. If I can go right from the problem happening, to a read test on all drives for 1GB/s.
It really feels as if there is an issue reading from memory and dumping to disk.
Tried removing the 15k 73GB SAS drives from the cache pool
Lowering/raising the dirty cache ratios and numbers.
Tried playing around with nr_request, and other tunables
Upgrading to 6.5.0 - which it still occurs after the upgrade
Please note: md_write_method is to reconstruct write. In my opinion it should be 100MB/s write and read from each drive, but when it has an issue - its between 2MB/s - 25 MB/s. Attached are a few screenshots of it starting to run fine, and then dropping way low. Also attached is my diagnostics report.
Also to note... I find it odd that when the issue happens, only 2 of the drives are reading to calculate parity during turbo write. Per my understanding, it should be reading all of the drives at once. If it makes a difference, these were added after the initial creation of the entire array. Also to note, in "iotop -oPa" -- unraidd has "IO>" at least 80-90% all the time. This might be an issue with adding the drives in after the initial array creation?
tower-diagnostics-20180314-0212.zip