System very slow/freezes with file backed Swap

[Sydney Meyer]

Hello,

i'm running a FreeBSD 11.0-RELEASE vm in AWS EC2 with 3-4 jails on it and after exactly one week, the vm seems to be freezing, i.e. sshd resets connections, console frozen, ICMP replies for 1-2 days, then timeouts) no messages in the logs, no messages on the screen.

I tried to reproduce this at home on Xen 4.4 with Linux 4.7 with small 256M memory VMs and found while running "periodic daily & periodic weekly":

- With file-backed Swap: behaviour like above
- With block-backed Swap: behaviour like expected (heavy swapping, eventual success)
- Without Swap: behaviour like expected (killed due oom)
- With encrypted block-backed Swap: behaviour like above

Is this to be expected?