I have inherited a server that is a Virtuozzo guest. I just noticed that /usr/bin/free is reporting 100% or near-100% memory usage; no shared, no buffers, no cache:
# free -m total used free shared buffers cached Mem: 4045 4045 0 0 0 0 -/+ buffers/cache: 4045 0 Swap: 0 0 0
All services are responsive. Both top and ps do not show any processes nearly close to 4GB of allocated memory.
Not to jump the gun but I've managed many Linux systems seen this situation. I vaguely remember reading that Virtuozzo has a dynamic over-committed memory management system, so I was wondering if that is it, and the striking results above are not cause for alarm.
Or should I begin to panic?
For the record, it turned out that a process was definitely consuming memory. It wasn't an artifact of Virtuozzo.