“A group is a system object — much the same as a user — except that no one will ever log in to the system as a group. The power of groups is in how they, like users, can be “assigned” to files or directories, allowing any group members to share the group powers.”— David Clinton, hackernoon.com
“Stalled means the processor was not making forward progress with instructions, and usually happens because it is waiting on memory I/O. The ratio I drew above (between busy and stalled) is what I typically see in production. Chances are, you're mostly stalled, but don't know it.”— Brendan Gregg, brendangregg.com
“You can additionally reduce latency by applying CPU affinity on each thread/process, e.g. nginx has worker_cpu_affinity directive, that can automatically bind each web server process to its own core. This should eliminate CPU migrations, reduce cache misses and pagefaults, and slightly increase inst…”— Alexey Ivanov, blogs.dropbox.com
“A service called fail2ban can mitigate this problem (edit: SSH being public) by creating rules that can automatically alter your iptables firewall configuration based on a predefined number of unsuccessful login attempts. This will allow your server to respond to illegitimate access attempts without…”— Justin Ellingwood, digitalocean.com