It's a bit like asking how long it takes to drive to work. Well, that depends, doesn't it? It depends on whether I'm driving a Ferrari or a Volkswagen beetle, on what the traffic conditions are, on the weather, etc. — but if I know all those things, then I can make a pretty good estimate. Predicting the capacity of a MID server works the same way.
There are two main factors to consider when estimating the capacity of a MID server: how much work do you actually need to get done within a given time period, and how many threads the MID server is Managing MID Server Resource Consumption...">configured to use. A couple of very rough rules-of-thumb you can use: a MID server can process about 2 probes per minute per thread, and there are about 7 probes per device on average. Both of those may vary a bit in your environment, depending on the mix of devices (for example, it takes more probes to discover Windows servers than it does for routers) and the speed of your network communications and MID server. Also, if your IP ranges are unusually large (say, /20 or bigger) and mostly empty, your MID server will spend more time pinging non-responding IP addresses, slowing things down a bit.
How does this translate into an estimate? Well, suppose you had a location with about 2,500 devices (a mix of servers, network gear, printers, and workstations) all together. Further suppose that you wanted Discovery to do its job between 6 pm on Friday and 3 am on Sunday each week — a "Discovery window" of 33 hours. Could a single MID server configured to use 25 threads do the job?
Using the rules-of-thumb, discovering 2,500 devices would require about 7â‹…2,500 = 17,500 probes. With 25 threads, the MID server can process about 2â‹…25 = 50 probes per minute. Therefore we can estimate that this work will take 17,500/50 = 350 minutes, or about 6 hours. This work should be easily completed within the allotted window...
