Hello all. I'm trying out the ExportSnapshot tool and it is extremely slow. I took a look at the code and I think I know why.
https://github.com/cloudera/hbase/blob/cdh4-0.94.6_4.4.0/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java#L635 In step 1 it is for some reason copying from fs1 to fs2. This basically means in a single threaded process we are copying an entire hbase table to another cluster. I can understand wanting to copy from fs1 to fs1 (i.e. different path on same fs), so as to dereference all the soft links of the snapshots. But why between filesystems? In step 2 you finally do the MR job, which makes much more sense, but as far as I can tell all of the files would already exist, as FileUtils.copy just does a recursive copy of all paths in a tree. Am I missing something? I appreciate any input. - Bryan
