I'd really appreciate some input on HBASE-8778 from the developers. Short summary: When opening regions, the region server (via FSTableDescriptors) scans the entire table directory to find the latest table descriptor file. On large tables this can make region opening slow as it invokes many round trips to the NameNode and a lot of data transferred. On our production cluster it really slows down our MTTR as it takes 10 minutes to open 200+ regions after logs are split.
I put a patch up there that is solving the issue for us, but not sure if it's the direction the community would want to go. Thanks for taking a look, Dave
