> You still have about 700M of free (unused) memory,
> so it looks
> like cache "underflow" for me. Cache is expected
> to use all
> available memory as long as it's not needed for
> apps and cache
> have something to cache.
>
> Maxim Dounin

Thank you ! I think this cache is "underflow" because this server hasn't many website on it.

> The cache adapts dynamically to the workload i.e.
> as long as you have free
> memory the operating system will try to cache data
> in there. Once you run
> out of free memory the os will begin to throw out
> cached information to
> satisfy allocation requests.
>
> The real amount of free memory (as in "memory that
> can be allocated by
> applications" also sometimes calles "available
> memoery") is free memory (as
> in "completely unused memory" that is shown in
> e.g. top or /proc/meminfo)
> plus cached memory.
>
> Regards,
> Dennis

Thank your for this valuable answer !!