According to the specs, the 2821 routers can only use up to 256MB on the Flash.
I have a 2821 with a 1GB card and the router boots up normally.
has anyone experienced or used a 2821 with more than its allowed flash?
ISR G1 (this includes the 1800, 2800, 3800) CF slots can take a maximum of 2Gb Type II CF cards. It can also take up to 2Gb of USB in any of the two ports (except the 1800). This includes the 860, 870, 880 and 890 ISR routers. I've used it up to 4Gb and I am confident to say: Stick to no more than 2Gb.
ISR G2 will take up to 4Gb.
Does this help?