Description of problem:
If gluster nodes get out of sync because their times do not line up many different types of issues can be encountered, the resolution for these issues is to configure NTP on each of the gluster nodes to have them sync to the same time source, however, the documentation does not state this as a required configuration or as a best practice.
The documentation needs a section that states that NTP is a requirement for each of a users gluster nodes and should provide information on setting up NTP.
Here is the NTP guide that's found within the RHEL6 documentation: http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Migration_Planning_Guide/ch04s07.html
In "Setting Up the Environment for Geo-replication"  section, under "Time Synchronization" heading, we have documented about time sync as "On bricks of a geo-replication master volume, all the servers' time must be uniform. You are recommended to set up NTP service to keep the bricks sync in time and avoid out-of-time sync effect."
Even in "Best Practices" section, we have mentioned that "set uniform time on all bricks..."
But yes, providing information/link on how to set up NTP will be helpful to users and I will add the same in Geo-replication chapter.
The updated Red Hat Storage 2.0 User Guide is published