The client does not want to spend the money to purchase a dedicated computer to run FM Server 17.
It's all about risk management: any configuration that is required for the non-FMS role can negatively impact the health of the FM files and the uptime of FMS.
Performance can also be affected obviously, that depends on what the machine otherwise does and what kind of load is expected for all the roles combined.
But usually it's not so much performance but the integrity and health of the FM solution and how big the risk appetite is for things to go wrong there.
Best practice is to not do it and best practices are condensed rules-of-thumb borne out of long and sometimes painful experiences by others.
If I were placed in a situation like yours I would thoroughly document the current state, document that there is an increased risk and suggest procedures to try and mitigate those risks. But make sure it's all documented so that the client is aware and that you have something you can point back to.
Are they willing to use FM Cloud or your own AWS/Azure instance in the cloud? That way the cost be more of a subscription model instead of capital expenditure.
FM Server can run on a computer in the office. Could be any computer.
But problem is that someone could steal it, restart it (for installing software) or just make copies of the database files.
It's usually better to have a separate computer in a locked room, which nobody uses for work, so the server runs 24/7.
But it still can be some spare Mac mini or iMac you don't need currently.
What exactly will be run on the computer, is it a users computer, or is it a server doing other functions?
If it is someone's personal computer you may find FMServer to be unreliable, if the user has a web browser open and that browser decides to use lots of RAM as they often do then FMServer services will start to shut down somewhat randomly.
Its better to use an old dedicated mac mini 2012 4 GB ram/ mechanical disk 500 GB than a SUPER 2018 mac mini used as FM server and also as an user machine.
Risk, shutdowns, restarts, proceses taking the cpu or the ram, etc, many things can happen, the users are completely unpredictable so try to avoid that, how much are you willing tonpay for a 3 hour shutdown on a busy day ? Invest at least twice that money in a server Its worth.
Those minis can cost $ 180- 240 on ebay or $ 200-500 on OWC,
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