I don't know the specifics about the pergola but here is a suggestion about anchoring it. Set your pergola legs on the patio and mark them. Use a screwdriver or flat nail bar to pry up only the pavers where the legs will go. Use one of those augur type bulb planter to drill a hole into the soil where the pavers were removed. Place the legs in the holes and pour concrete into the hole and around the leg. Smooth it out and cover the space where the paver was. You can color the concrete by spraying it with ironite fertilizer to stain it a brown or rust color or with copper spray to change it to bluish-green.

Since there is minimal disturbance of paving units and sub-grade, the steel rod approach your link described, is an easy method for securing the pergola posts to an existing paved surface. However, if a typical system of horizontal beams and stringers are used, and support posts are sized sufficiently, a 12' x 12' pergola is on the large side and quite heavy.

I personally don't think the 3" bluestone is capable of supporting that dead-load - without potential failure. Cracking could occur and without diagonal bracing at the beam to post connections, there may not be enough lateral resistance to prevent the whole freestanding structure from racking.

Consider setting concrete footings such as tsmith recommends. I would however, approach it in a different way. Remove the paving stones at each proposed post location to provide enough clearance for digging holes deep enough to go below the frost line of your area. Choose a method of digging, either with a manual post-hole digger, or a rented, gas-engine post hole auger. I imagine your posts will be at least 6 x 6s - perhaps even 8 x 8s.

If you elect to use posts embedded directly into concrete for maximum stability - accept the fact that regardless of using PT pine or cedar, the posts will eventually rot - even with a canted concrete top for water drainage.

Consider this method as an alternate: Dig a hole at least 10" in diameter, and set each post over a compacted bed of gravel or crushed stone below frost. The use of compacted crushed stone poured into the spaces around each post, allows ground water to be irrigated down past the posts before it has a chance to rot the wood. Add the stone in 6" lifts, compacting each layer with a tamping post. Fill the holes up to the sand base, cut each paver and reset as necessary.

Another proven technique is to cast round galv. steel fence posts, or flat steel plates into each concrete footing, with at least 18" extending above finish grade level. The round posts would extend into holes drilled into each post bottom - then secured by through-bolts, countersunk and plugged.

Flat plates would equal the width of each post, with plate thickness determined to oppose bending resistance (3/8" to 1/2" might be sufficient). The plate ends extending from the concrete footing would fit into slots cut into each post bottom, then through-bolted such as with the round post method.

This sounds like a fun project and will enhance the great job you've already completely on the patio. But in my opinion, there is no easy way out for securing the pergola, for ensuring the longevity of the structure and the safety of your family and guests who may enjoy it.

I want to purchase a metal frame pergola for my brick paver patio. The model is designed to mount to the posts to the concrete patio. Is there any anchor that I can but for it? Digging hole for cement base is my last option.