i'm preparing CCIE security ,
first i watch 2 or 3 videos then read it from ATC and try it on GNS3 ,
my Question is it enough to practice ATC small labs on GNS3 , EX. ASA failover , IPS , WSA , ISE ,ACS
or i should rent a rack ??
The small labs are good for your hands-on on the separate topics. But the small labs will take you maximum a few hours? In the end you will have to sit for a whole day doing several tasks which are related to each other. In the full labs you will have to configure some feature and make sure the necessary traffic will flow through several routers and firewalls. This you will not practice in a small lab.
So focus on the small labs to make sure you understand the topics and are able to configure them. And then go for the more advanced labs (if necessary go for the rack rentals).