Bad performance issue in LXC, using Swap


Nov 18, 2023

I use sabnzbd on a LXC in proxmox. I noticed that the download drops to almosst zero, then to zero when an unpack starts. Unpack is done via unrar from debian non-free packages. I thought maybe it was too much for the HDD so I put the incomplete temp folder to an mount on the LVM (SSD), but it is the same behavior. When the unpack finishes, the download resumes with normal speed and sabnzbd becomes responsive again. There is NO high CPU usage for the container, so there must something going wrong, badly..

At one pont the system started using 100% swap, even there wa only 20% RAM usage. I reboot fixed it, but it uses like 1-5% still. my other LXCs dont use any swap. I also increased the RAM for the LXC to 2GB, without any change. There is plenty of RAm left. Dont know if the Swap Problem is linked together.

Does anyone have an idea?

I stress tested the system + the LXC with "stress" from stress-ng package. It works as expected with high load. So I guess it must be a prolme with sabnzbd/unrar integrations.

best greetings


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