Thank you St.Ack. This helps a lot.. :)
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Stack Sent: Tuesday, December 28, 2010 11:02 PM To: [email protected]; [email protected] Subject: Re: Query reg hbase and hadoop append We have been concentrating on delivering an hbase that works with hadoop's branch-0.20-append branch and CDH3. We've not spent time on proofing an hbase on top of hadoop 0.21. I myself haven't tried it in a while. There is reflection code around the sync call which tries to figure which version of Hadoop we are on top of. I'd imagine that while it might work, it might not be as performant as when run against hadoop 0.20 append since this is where we've been spending our time. Here is our story on hadoop versions for the coming 0.90.0: http://people.apache.org/~stack/hbase-0.90.0-candidate-2/docs/notsoquick.htm l#hadoop (Is this clear? Should we add anything?). As to why we're in this state where we are NOT up against the latest version of hadoop, the story is a little involved. I'll spare you the torturous detail. In short, the next major HBase release was to run against hadoop 0.21 but when we learned, belatedly, that its release was delayed with no guarantees regards when it would drop and that it was not going to be installed (or tested) by the 'big boys' -- Y!, FB, etc. -- we lost all enthusiasm for hadoop 0.21. We figured no one would run an hadoop 0.21 in production. Our focus shifted to the append branch in 0.20 because this was a relatively minor deviation from the pervasive hadoop 0.20. We could envision folks installing the append branch to get an hbase that-did-not-lose-data and running this hadoop in production because it was close enough to hadoop 0.20 and at least one of the big teams was running it -- i.e. fb -- or something very close to it. A bunch of effort was sunk into making sure HBase worked on this branch and that it was performant. Cloudera's CDH3 since b2 has had an append. Its provenance is the hadoop 0.20-append branch. Not hadoop 0.21. Hope this helps, St.Ack On Tue, Dec 28, 2010 at 12:43 AM, Gokulakannan M <[email protected]> wrote: > hadoop 0.21.0 has been released with the stable hdfs append feature.. > > > > Should we do anything in hbase(modify / apply some patch) to use this hdfs > append feature or hbase takes care of this in-built?? > > > > from web i've seen that this append feature(hdfs-265) is different from what > hbase expects(hdfs-200).. > > > > can anyone pls explain the background??? > > > > > > Thanks, > > Gokul > > > > > >
