> Given the above, I see two possible reasons why the cache volume
> is only filled at 50%:
>
> 1. You've run out of keys_zone size.
>
> 2. You've run out of resources requested frequent enough to be
> cached with proxy_cache_min_uses set to 2.
>
> It should be easy enough to find out what happens in your case.
>

It seems possible reason is keys_zone size. Will look into by increasing the same and trying different permutations.

As in general 1M stores around 8000 Keys, what could be probable formula for keys_zone size with proxy_cache_min_uses.

Since it keeps information of all requested resource so it would highly depend upon number of requested resources.

In my case number of request per sec is around 1000 i.e. 36 Lakhs per hour during peak hours