When NN starts to load fsimage, it does
A debug msg is issued at the beginning with the fsimage file name, then at the end an info msg is issued after loading.
If the fsimage loading failed due to corrupted fsimage (see
HDFS-9406), we don't see the first msg. It'd be helpful to always be able to see from NN logs what fsimage file it's loading.
1. Change the above debug to info
2. If exception happens when loading fsimage, be sure to report the fsimage name being loaded in the error message.