Saving a system dump while in multi-user state

You can obtain a system dump while the system is up and running, with dumpmemory. This command does not interfere with other things going on in the system, so users can be active on the system when you use it. This makes it a very useful tool for debugging the cause of poor performance of an application, or of a sluggish system. However, because memory is constantly changing in system state 3 (multi-user state) some of the information may not be valid. See dumpmemory(1M) for complete information on its use.