working at the premises of a client
the client has a server machine with 256 GB
memory consumption is 90%
this is because Qlik caches calculations and other stuff no?
is there a configuration on the QMC via which I can change the consumption to be 60% instead?
Assuming the QV Server Box is dedicated and not running other applications, as recommended. Then I would leave it it as is with the defaults, as it is designed to use RAM for massive caching which good.
Consuming 90% of RAM should not cause any issues. If it is then could share what the issues are ?
the issue is that while consuming 90% of the Ram then some tasks are running and is causing the server to go down and end users receive no server message in the access point
What version of Qlik You are on?
Why not try by migrating to new version.
For temporary fix
If this is just Caching of ram. I would prefer to restart qlikview server service via batch file at specific interval to clear cache if any.
If you leave the QMC->Working Set Limit->High value set at 90%, that means that your QVS is allowed to consume 90% of the total RAM amount in your server. 256 * 0.9 = about 25GByte is left untouched.
All other QlikView services including any occasional Reload job run outside of this memory allotment. Let's say that your OS needs about 2GB of RAM, then your QlikView services and reload processes (QVB.exe) should do their magic in about 23GB of RAM. Is that enough? If not, you should lower your Working Set Limits so that more RAM is set aside for other services and reload tasks.
BTW you can monitor RAM consumption either live using Task Manager, or programmed for extended periods using Performance Monitor or another Windows resource monitoring tool.