I started with a web server, and poller for NPM, APM, etc on a single physical server.
We now have two pollers monitoring over 16000 devices.
My initial install was on the system (C:\>) partition.
The system disk now has a disk queue length of just less than 5; performance of the web server / Poller is poor.
I would like to move this installation to a different array with more spindles on the same server.
How do I go about doing this with minimal down time?
You may want to consider a 3rd poller (a 2nd additional polling engine) first, if downtime is a significant issue. Otherwise, follow the instructions in the SolarWinds Technical Reference "Orion NPM Migration", but keep in mind that you will have some down time during your migration.