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.
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.