Hi all,
I need ur help plz
how sun cluster work and i need good reference for that.
ur cooperate is appreciated
If you tell Sun you are insterested in buying a cluster licence from them (they are pretty costly), they'll bend over backwards (you might be able to swing a free training course even) to give you any info you need. Grab your nearest Sun account manager 
do any one know a good video in this topic???
Erm, as DukeNuke2 pointed out. Go to docs.sun.com: Sun Cluster 3.2 2/08 (Sun Cluster 3.2 2/08 Documentation Center) - Sun Microsystems
It's free to download and use, the docs have everything you need. And yes, in three clicks from the docs site, there are videos (docs->wiki->videos):
Sun Cluster Goes to the Movies - Sun Cluster - wikis.sun.com