Summary indexing sound perfect for your needs.
Understand that summary indexes save statistics as data, not the data they were generated from, so spend time to decide exactly what statistics you want to save. For example: CPU - 5 minute average, 5 minute min, 5 minute max, and a time stamp per server. This will boil down 5 minutes worth of CPU logs for all servers into just 5 pieces of data per server, and save it in a separate index, which makes it very fast to search. The catch is, the data in the summary index cannot be rehydrated - a new search on the raw data is necessary.
... View more