You could manually edit the VERSION file in order to match the datanode and namenodes id's.
2012/6/27 Hank Cohen <hank.co...@altior.com> > [nit] First of all I think that the datanode storage location property > should be simply dfs.data.dir not dfs.datanode.data.dir (this from > src/hdfs/hdfs-default.html)**** > > ** ** > > Both the namenode storage directory and the datanode storage directory are > defined relative to hadoop.tmp.dir so simply changing that directory will > change both of the subdirectories. But this doesn’t allow me to change > back and forth without errors.**** > > > I get an error when I try to change hadoop.tmp.dir to a directory that > already contains a hadoop file system.**** > > The error is: > 2012-06-27 10:40:44,144 ERROR > org.apache.hadoop.hdfs.server.namenode.NameNode: java.io.IOException: > Unexpected version of the file system log file: -333643776. Current version > = -32.**** > > [Does anyone want to see the java stack trace?]**** > > ** ** > > When I look at the VERSION files (hadoop.tmp.dir/dfs/name/current/VERSION) > **** > > the only difference I see is that namespaceID is different. I think > namespaceID probably should be different, it is a different file system.** > ** > > ** ** > > Thanks for any guidance,**** > > Hank Cohen **** > > ** ** > > ** ** > > *From:* Konstantin Shvachko [mailto:shv.had...@gmail.com] > *Sent:* Monday, June 18, 2012 5:12 PM > *To:* hdfs-user@hadoop.apache.org > *Subject:* Re: Changing where HDFS stores its data**** > > ** ** > > In hdfs-site.xml you should specify > dfs.namenode.name.dir > for NameNode stoareg directories or / and > dfs.datanode.data.dir > for DataNode storage > > Changing temporary directory location changes the default for storage > directories. > Which should also work. You might want to check the message the NameNode > loggs when it fails. > > Thanks, > --Konstantin**** > > On Mon, Jun 18, 2012 at 3:47 PM, Hank Cohen <hank.co...@altior.com> wrote: > **** > > I am trying to do some testing with different storage configurations for > HDFS but I am having difficulty changing the storage destination without > having to re-initialize the whole file system each time I change things.** > ** > > **** > > What I want to do: Set up and run some test cases with two different local > file system configurations. Think of it as having different local disks > with different performance characteristics. **** > > > What I have done so far it to change the xml in core-site.xml to change > the hadoop.tmp.dir property. Let’s call this dir1.**** > > I can set this up and format the file system without any problems, run my > tests, shut down and change core-site.xml again to dir2.**** > > Again I can format dir2 and run my tests OK but when I try to switch back > to dir1 I can’t get the namenode to start. I find that I have to remove > all of the directories and subdirectories from dir1 then reformat and start > over with nothing in the file system.**** > > **** > > Is there an easy way to do this without having to reinitialize the whole > HDFS each time?**** > > **** > > *Hank Cohen***** > > **** > > +1 732-440-1280 x320 Office**** > > +1 510-995-8264 Direct**** > > **** > > 444 Route 35 South**** > > Building B**** > > Eatontown, NJ 07724 USA**** > > **** > > hank.co...@altior.com**** > > www.altior.com**** > > **** > > [image: Description: EmailBug]**** > > **** > > ** ** >
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