Blazing fast upload but slow download speed from TrueNAS FTP

[anphex]

Hello from Berlin everyone,

I noticed that my newly set up TrueNAS system, which works flawlesslsy so far, uses full 1Gbit performance when uploading data but the download speed don't go above 6 Mbit. How would I go about checking the reason behind this problem? Any cli tests?
There is no performance management set up. My guess so far is that ZFS cache saves the day when writing/uploading to the server so it appears fast.

My system:
Intel i3 6100 CPU
16 GB DDR4 2133 Mhz Ram
MSI h110m pro-d
RaidZ running on 3 HDD, 2x 5400 and 1x 7200 RPM from WD and Toshiba
OS Version:
TrueNAS-12.0-U1

Thank's for any help in advance!

 

[Chris Moore]

Hello from Berlin everyone,

Hello. Welcome to the forum.

My guess so far is that ZFS cache saves the day when writing/uploading to the server so it appears fast.

That is very likely the correct answer.

I noticed that my newly set up TrueNAS system, which works flawlesslsy so far, uses full 1Gbit performance when uploading data but the download speed don't go above 6 Mbit.

Normally, in a pool such as you describe, your read performance should be controlled by the slowest drive in the set.
However, this could be caused by the pool hardware configuration.
Exactly how are these drives connected to the system board and exactly what model are the hard drives?

It is possible that you have some drives that use SMR technology, which has been tested and proven to perform VERY poorly in ZFS.
If that is the case, you will need to replace the SMR drives both for the performance aspect and because they also have a higher propensity to be seen by ZFS as failed. They sometimes get marked as failed by the file system because they can take too long to respond to requests for data and ZFS sees that as a failure. The slow response time could also be the reason for your slow read rate.