vmstat 10 2 will monitor an interval of 20 seconds, whereas vmstat 1 10 will only cover 10 seconds. Both are not sensible invocations for long-term monitoring. Try vmstat 600 (every 10 minutes) or something like that. The reason why you want a long interval is that you are not interested in any "spike" but the average usage of a system. Further, every polling of the stats also places a (slight but non-zero) load onto the system. You don't want your monitoring system to create the bottleneck it is intended to prevent.

Yes, correct

You don't want to avoid swap usage you want to avoid swapping activity. Something being in the swap doesn't hurt - putting it there and getting it back into memory again is what hurts. Therefore looking at a number which only tells you how much swap is used doesn't tell you what you really want to know.

Sometimes this is the case - it might be better overall if the damage you take by swapping something out is outweighed by the gain you may get from the memory freed that way which can be used otherwise. In general (but notice: "in general" doesn't mean "always") it makes sense to size a system in a way that swapping doesn't take place in normal operation. Swap is generally a "plan B", not the "plan A".


Yes. But in a professional environment it makes sense to size a system sufficiently. Memory does not come free of charge and it pays (or rather - saves) to give a system as much as it needs - but not more. It is the job of a systems administrator to walk that fine line between oversized (=wasting money) and undersized (=hurting the purpose).

You might want to read this little introduction to performance tuning and monitoring for more details about swapping.

I hope that helps.

bakunin