HDFS-1435, we introduced a new option to store fsimage compressed. And this can avoid that It consumes a lot of network bandwidth when SBN do uploads a new fsimage to ANN. When lots of network bandwidth was consumed, it will affect ANN to deal with normal RPC requests or sync edit logs.
This is a very useful setting when our fsimage file is very large. However current description of this setting is too simple, we can document this more.