Andrzej Bialecki wrote:
So far I learned that the secondary namenode keeps refreshing periodically its backup copies of fsimage and editlog files, and if the primary namenode disappears, it's the responsibility of the cluster admin to notice this, shut down the cluster, switch the configs across the cluster to point to the secondary namenode, start a primary namenode on the secondary namenode's host, and restart the rest of the daemons.
If you use DNS to switch the namenode from the primary to the secondary, then no configuration changes or other daemon restarts are required. I think that is the best practice.
Doug
