If you servers stay at the minimum working set limit, I would say that it may be time to start reflecting on a possible RAM purchase. The server RAM load is not at its maximum, because you still haven't reached the max working set limit. When your servers stay at the maximum limit, you should put on your coat and hurry to your local store to buy some more RAM.
Tools like the QlikView Application: System Monitor v5.1.23 can help you in detecting trends in memory usage. That way you can plan for a RAM extension well before it is really needed.
Is it not so that Qlikview will not delete old cache/ optimize the memeory and will keep piling up the old cache until it reaches the working set min. That means that we might still have a lot of memory left and it is only being used by old cache. Qlikview will only start deleting old cache once it has going beyong working set min.
In this case, buying a new set of ram would be a waste if we will have a lot of memory left but Qlikview has not optimized it
Well, I was only suggesting to buy RAM when the server reaches the max working sel limit and stays there. Two commonly occurring events can influence memory usage in a dramatic way:
- adding a pack of users to one or more documents
- publishing new documents with a considerable footprint
These may seem to have predictable impact with respect to memory usage, but since QVS memory usage per document isn't really a transparent affair (not taking into account that QDS may add a considerable uncertainty factor if you run both on the same machine), making correct calculations may be close to impossible.
I think the best thing you can do is monitor memory usage and do trend analysis on a regular basis.