Ryan Rawson and I have been running performance experiments where we swap out MapFile and put in its place a customized HADOOP-3315 tfile and a format that Ryan wrote himself named rfile. Its looking like Ryans' rfile has many benefits over our current MapFile based format and that we'll likely move on to it over the next week or so. If you're interested, see toward the end of HBASE-61, the new file format discussion doc http://wiki.apache.org/hadoop/Hbase/NewFileFormat, and the coarse performance stats here: http://wiki.apache.org/hadoop/Hbase/NewFileFormat/Performance.
Comments welcome either here or up in the issue, Thanks, St.Ack
