السلام عليكم ورحمة الله وبركاته
ما معنى كلمة cluster ؟
ما معنى session?

لو امكن الشرح بمثال فيكون افضل

واشكركم كثيرا على الرد السريع للاسئلة المعروضة ..وجزاكم الله خيرا

cluster is
a group of machines that are networked together and used 
as a single unit to run parallel programs

session is 
The set of events that occurs from when a user connects to the Oracle database 

السلام عليكم

cluster mean that more than server connected together , if any server down the other can continue and when that up it will take all data that losted...

every server have node to saw all aplication on the servers for example u have 2 servers .. server1 have node1 and server 2 have node 2.
when u want to saw any application like that oracle db from server 2 u must connect from node 2.