In order to uniquely identify a block in hadoop 2.2, you are going to need both a block and a block pool ID. You can construct a Block object with those two items.
On Wed, Jan 15, 2014 at 8:46 AM, Yu Li <car...@gmail.com> wrote: > Dear all, > > As titled, I actually have two questions here: > > 1. In current releases like hadoop-2.2.0, is block id unique and able to > locate a Block in HDFS? I'm asking because I could see HDFS-4645 is trying > to resolve the uniqueness issue. However, from the code comment it seems > block id is expected to be unique > > It's expected to be unique within a block pool. You can get the block pool ID you are using from your FSNamesystem object in 2.2. best, Colin 2. It seems there's no method to get a Block object through a block id. > However, there's some scenarios need such method, like if I use the > FavouredNode feature to create logical datanode group and planned to put > some data within a group, then I might need to periodically check whether > there's block somehow placed outside the group, and move it back. In such > scenario, I would need to first get block ids, then move. But to move them, > it seems we need a Block instance to initiate the ExtendedBlock object. > > Any suggestion, or reference to existing JIRA would be highly appreciated, > and thanks in advance! > > -- > Best Regards, > Li Yu >
