I was running Centos 6 with Virtualbox for 2 xenial-vm-webservers (1 CPU/512 MB RAM) very light static pages and low traffic. Host is 8-core Intel® Xeon® CPU E3-1240 V2 @ 3.40GHz with 12 GB RAM (mainly a samba server)(Dell poweredgeT110 II).All was OK.
Migrated everything to Xenial with 2 xenial-vm-webservers. Now everyday when unattended-upgrades (has a real package installation) are running in baremetalhost there is info - and I cant reach the webservers.
INFO: task apache2:18083 blocked for more than 120 seconds.
We have gigabit ethernet connected through German National Research and Education Network https://www.dfn.de/en/ so it is definitely not a network issue.
I even increased the RAM and CPU allowance.
lxc config set www1 limits.memory 1024MB lxc config set www1 limits.cpu 2
apache gets blocked at this time. This never happened before with virtualbox. I assumed that lxd(lxc) must consume less resources and hence must not get blocked or am I mistaken? host Root is EXT4 and data in ZFS.
Any suggestions. Thanks
sysctl -a vm.dirty_background_bytes = 0 vm.dirty_background_ratio = 10 vm.dirty_bytes = 0 vm.dirty_expire_centisecs = 3000 vm.dirty_ratio = 20 vm.dirty_writeback_centisecs = 500 vm.dirtytime_expire_seconds = 43200