There is also some work underway to add in HA and failover to the namenode. You might get more success if you send your note to hdfs-dev instead of common-dev. One other thing that can sometimes get a discussion going is to just file a JIRA for it. People interested in it are likely to start watching it, and you can often have a good conversation there about it.
--Bobby Evans On 9/28/11 8:27 AM, "Ravi Prakash" <ravihad...@gmail.com> wrote: Hi Mirko, Its seems like a great idea to me!! The architects and senior developers might have some more insight on this though. I think part of the reason why the community might be lazy about implementing this is because the Namenode being a single point of failure is usually regarded as FUD. There are simple tricks (like writing the fsimage and editslog to NFS) which can guard against some failure scenarios, and I think most users of hadoop are satisfied with that. I wouldn't be too surprised if there is already a JIRA for this. But if you could come up with a patch, I'm hopeful the community would be interested in it. Cheers Ravi 2011/9/27 Mirko Kämpf <mirko.kae...@googlemail.com> > Hi, > during the Cloudera Developer Training at Berlin I came up with an idea, > regarding a lost name-node. > As in this case all data blocks are lost. The solution could be, to have a > table which relates filenames and block_ids on that node, which can be > scaned > after a name-node is lost. Or on every block could be a kind of a backlink > to the filename and the total nr of blocks and/or a total hashsum attached. > This would it make easy to recover with minimal overhead. > > Now I would like to ask the developer community, if there is any good > reason > not to do this? > Before I start to figure out where to start an implementation of such a > feature. > > Thanks, > Mirko >
