I've got an SSO server (Tomcat) built on CAS (Jasig) protocol. Many clients (web, desktop, android, ios) use it to authenticate users. If I restart application server, all the clients can't get a new ticket based on a given TGT. They have to go through authentication process again.
There are many TGT policies documented at CAS wiki (https://wiki.jasig.org/display/casum/ticket+expiration+policy). Unfortunately I haven't found if it is possible to configure CAS server the way it won't forget TGT after server restart. Is it even possible?
Disclaimer: I'm the Chairman of CAS and founder of CAS in the cloud (https://www.casinthecloud.com).
In fact, it depends where the TGT are stored (in which tickets registry). If it's a memory one, tickets will be lost after a CAS server restart. But you will keep your tickets after a server restart if you use a database, Memcached...