allanp81

I logged the exact same issue. Copying to a non-cache enabled shared doesn't have the same issue. No-one seemed to have an answer as to why.

I would've thought cache pool (or ssd shared via unassigned drives) was your only real option here as the drives are always available unlike normal array drives that will probably spin down.

@RedReddington Is this when copying to array with cache drives or straight to disks?

I have a mix of disks, could that be the problem? One is a Samsung SSD 850 PRO and the other is a SanDisk SD8SB8U512G1001. Running Trim didn't help either, I'll have to look into maybe replacing the drives then. I don't have anything spare though so if replacing doesn't fix I've wasted £100 or so.

Unless I'm being stupid, surely they can handle more than 50Mb/sec and not fluctuate so much and also not cripple the server at the same time?

@johnnie.black So by switching from "Auto" to "reconstruct write" seems to solve the issue when copying directly to the array, doesn't fix the issue with cache though obviously. This also seems to solve the issue of slow/intermittent speeds when backing up to my other server. Is there a potentially that my cache drives have issues even though nothing is reported as being wrong? I have 2 drives that aren't the same make but are the same size.

I can understand that if copying to a share without cache enabled, I'd expect to see 40-50Mb/sec, but would it not be consistent rather than fluctuate so much? Also, when writing direct to cache I see exactly the same symptoms but it's worse in that it seems to basically cripple my server until sometime after the copy finishes! I don't recall seeing these issues prior to 6.8.x. I also see similar when backing up to my other server which is also now running 6.8.x and running on entirely different hardware with no cache drives specified.

Interestingly as well, copying from the same client machine to my win10 VM on my server copies at ~110meg consistently until the copy finishes. The VM lives on a btrfs pool created outside of the array and mounted using the unassigned devices plugin so I know that there is no issue with the network cabling etc. Copying from the VM then to array then exhibits the same issue with the slowing down and then inconsistent speed fluctuations.

Here is a visual example of what happens: As you can see, it starts of maxed out and then just proceeds to drop and then go all over the place.

Doing some more testing, and it seems that while copying to a non-cache enable share still slows down significantly, it doesn't seem to cripple the server like copying to a cache enabled share does. It still suffers exactly the same speed drop from ~110Mb/sec to anywhere between 10 and 50 meg/sec, it fluctuates constantly.

OK, see attached. downloadbox-diagnostics-20200120-2205.zip

For some reason, since upgrading to 6.8.x it seems that my server becomes somewhat unresponsive if I copy large files (10Gb+) across my network to it. I have tried copying to a share that has cache enabled and also to a share with no cache enabled. I see the same symptoms whereby for about the first 20-30 seconds it copies at ~110Mb/sec, maxing out a gigabit connection but then starts to drop massively, sometimes down to single digit Mb/sec. While this is happening it becomes almost completely unresponsive at times. Dockers become inaccessible, or just take a very long time to respond. I know I need to attach my syslog, but there are literally zero errors stated in it.

I kinda guessed that, but I couldn't figure out the docker run command as it fails when I try.

I mean even just getting the docker installed.

Did you get this working? I'm really struggling.