I am running a fresh build of Unraid 6.12.0-rc7, but I experienced the same on RC6 and RC5. My CPU consistently fluctuates between 40% and 60% with spikes about every 10 seconds to 90% and 100%. I have narrowed it down to writing data to the array. The second the array is being written to, the shfs process starts using >100% CPU. I tested it by booting into safe mode, starting the array with just my torrent client downloading a single torrent at ~35MBps. I have tried qBittorrent, Deluge, and Transmission with the same results. At the same time, if I try to do any file copying, either local (drive to drive) or over the network it slows to 6-10MBps local 0-3MBps over network and my torrent speeds drop to ~15MBps. Stopping the torrent client completely and performing a transfer gives me decent transfer speeds of >100MBps local, but again with >100% CPU usage on the shfs process. If I stop the array and mount the exact same drives, I get >150MBps transfer rates and no spikes in CPU usage.

 

I have been pulling my hair out trying to figure this out. In the pass couple weeks I have built and destroyed pools, arrays, and even raid0 arrays using both ZFS and BTRFS, and now have a standard Unraid array using XFS. It has been a while since I used Unraid, but I do not remember this problem previously. Does anyone have any ideas?

unraid-diagnostics-20230609-1917.zip

Similarly my test server with ZFS drives, in the Unraid Dashboard it shows continuous CPU usage (20-60%) when just writing data to the array. With erratic high jumps as well.

 

However .. according to htop it is mostly just 2-5% in total.
And htop shows (in this order) krusader (docker) , htop itself , a handfull of shfs , and tailscale (plugin) as highest CPU users.

 

Unraid Version: 6.12.2 

Array consists of 2 ZFS drives and one XFS drive. Writing only to a ZFS drive during abovementioned. I did no further tests, just sharing a observation about high Unraid Dashboard CPU graphs. Actual network traffic during all of this is mostly between 40MB .. 250MB per second. (2.5Gbps)

unraid2-diagnostics-20230718-2227.zip

Edited July 18, 20232 yr by Barry Staes
Added version details + diagnostics

@theimmortal if you see/reproduce High consistent CPU usage in the Unraid Dashboard again, do this test:

Look at the "top" or "htop" command in the console, what kind of CPU usage to you see?

 

As said above i see a 10x deviation between the two.