SSN = checkpoint node. I think multiple checkpoint node is supported in 0.21.
On Wed, May 25, 2011 at 9:53 PM, ccxixicc <ccxix...@foxmail.com> wrote: > > Hi,all > I'm testing hadoop with two secondary namenode ( I'm using hadoop-0.20.2) , > and get some errors. So I did a few search. But first I got confused about > SNN: > > From > http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Secondary+NameNode > says: > 'The secondary NameNode merges the fsimage and the edits log files > periodically and keeps edits log size within a limit.' > But from > http://wiki.apache.org/hadoop/FAQ#What_is_the_purpose_of_the_secondary_name-node.3F > says: > 'The only purpose of the secondary name-node is to perform periodic > checkpoints. The secondary name-node periodically downloads current > name-node image and edits log files, joins them into new image and uploads > the new image back to the (primary and the only) name-node' > > So whether or not will SNN upload the image back to NameNode? > If so, what's the difference between SNN and checkpoint node? > > > Back to the two secondary namenode question > I had namenode and two SNN on three separate machines. Each one SNN with NN > work fine. But if I start two SNN with NN, it failed: > The NN says: > WARN org.mortbay.log: /getimage: java.io.IOException: GetImage failed. > java.io.IOException: Namenode is not expecting an new image UPLOAD_START > .... > WARN org.mortbay.log: /getimage: java.io.IOException: GetImage failed. > java.io.IOException: Namenode is not expecting an new image START > > > The SNN says: > ERROR org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode: Exception > in doCheckpoint: > ERROR org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode: > java.io.FileNotFoundException: > http://192.168.1.22:50070/getimage?putimage=1&port=50090&machine=192.168.1.23&token=-18:785478552:0:1306378278000:1306378218810 > at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown > Source) > at > org.apache.hadoop.hdfs.server.namenode.TransferFsImage.getFileClient(TransferFsImage.java:151) > at > org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.putFSImage(SecondaryNameNode.java:280) > at > org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.doCheckpoint(SecondaryNameNode.java:320) > at > org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.run(SecondaryNameNode.java:225) > at java.lang.Thread.run(Unknown Source) > > What's wrong? Multiple SNN not supported in hadoop-0.20.2? > > Thanks. > > > >
