It depends on your environment and how it is going to be used.if it is the only server (or one of a very small number) and needs very limited access the choice would be per server. the most basic question here is how many concurrent (at one time) connections will be needed. if it is small this is the one for you (small office, workgroup, small school). The benefit to this one is you have a one time chance to change to the other mode if it is not working out for your environment. The draw back to this mode is once all the connections are taken up any new ones will be denied. While the per user mode will only be loggedif there are a lot of servers in your environment and they need frequent and widespread access to the server the "per user" is for you. If you choose this one first, it is permanent! The best example of why you would pick this mode is say you have users that will connect to the SQL server with their PDA computer laptop and phone. if he connects with all these at the same time it is considered one connection. This one is more economical once you get into large groups and organizational structures.if you are still not sure which one use the per server.
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