JGroups Protocol FD SOCK

!!!External

• User Manual FD http://www.jgroups.org/manual/index.html#FD_SOCK
• JGroups Wiki http://community.jboss.org/wiki/JGroupsFDSOCK
• http://community.jboss.org/wiki/FDVersusFDSOCK

Internal

• JGroups

!!!Overview

Failure detection protocol based on a ring of TCP sockets created between group members. Each member in a group connects to its neighbor. Last member connects to first, thus forming a ring. Member B is suspected when its neighbor A detects abnormally closed TCP socket presumably due to a node B crash. However, if a member B is about to leave gracefully, it lets its neighbor A know, so that it does not become suspected.

One FD_SOCK disadvantage is that hung servers and/or crashed switches will not cause sockets to be closed. Therefore hung members will not be suspected and network partitions due to switch failures will not be detected. A solution to this problem is to use both FD and FD_SOCK failure detection protocols.

!!!Configuration Sample

{{{

   <FD_SOCK start_port="${jboss.jgroups.udp.fd_sock_port:54200}"/>

}}}

!!!Recommendations

See [FD_ALL Recommendations|FD_ALL#Recommendations]

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