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https://issues.apache.org/jira/browse/SOLR-6305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14081186#comment-14081186
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Timothy Potter commented on SOLR-6305:
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Thanks Mark, nice approach to config overriding, unfortunately, looks like
Hadoop doesn't want this to work for us :-(
I tried your suggestion and added some debug to the HdfsFileWriter and here's
what I see:
In HdfsFileWriter, fileSystem.rep=4 but fsDefaults.getReplication=2
In the main etc/hadoop/hdfs-site.xml (cluster wide default), dfs.replication=2
I added etc/solr/hdfs-site.xml with dfs.replication=4 and then
-Dsolr.hdfs.confdir=/Users/thelabdude/dev/lw/tools/hadoop-2.2.0/etc/solr
The fileSystem and Configuration objects being used by Solr definitely see:
dfs.replication=4. However, it is still coming out with the cluster-wide
default of 2! Digging into the Hadoop code a little, it looks like the
DistributedFileSystem implementation of FileSystem gets its FsServerDefaults
from DFSClient, which uses: serverDefaults = namenode.getServerDefaults();
That looks to me like the server defaults are coming from the namenode
(cluster-wide) and totally disregarding what's in the Configuration object
setup by HdfsDirectoryFactory! Ugh.
> Ability to set the replication factor for index files created by
> HDFSDirectoryFactory
> -------------------------------------------------------------------------------------
>
> Key: SOLR-6305
> URL: https://issues.apache.org/jira/browse/SOLR-6305
> Project: Solr
> Issue Type: Improvement
> Components: hdfs
> Environment: hadoop-2.2.0
> Reporter: Timothy Potter
>
> HdfsFileWriter doesn't allow us to create files in HDFS with a different
> replication factor than the configured DFS default because it uses:
> {{FsServerDefaults fsDefaults = fileSystem.getServerDefaults(path);}}
> Since we have two forms of replication going on when using
> HDFSDirectoryFactory, it would be nice to be able to set the HDFS replication
> factor for the Solr directories to a lower value than the default. I realize
> this might reduce the chance of data locality but since Solr cores each have
> their own path in HDFS, we should give operators the option to reduce it.
> My original thinking was to just use Hadoop setrep to customize the
> replication factor, but that's a one-time shot and doesn't affect new files
> created. For instance, I did:
> {{hadoop fs -setrep -R 1 solr49/coll1}}
> My default dfs replication is set to 3 ^^ I'm setting it to 1 just as an
> example
> Then added some more docs to the coll1 and did:
> {{hadoop fs -stat %r solr49/hdfs1/core_node1/data/index/segments_3}}
> 3 <-- should be 1
> So it looks like new files don't inherit the repfact from their parent
> directory.
> Not sure if we need to go as far as allowing different replication factor per
> collection but that should be considered if possible.
> I looked at the Hadoop 2.2.0 code to see if there was a way to work through
> this using the Configuration object but nothing jumped out at me ... and the
> implementation for getServerDefaults(path) is just:
> public FsServerDefaults getServerDefaults(Path p) throws IOException {
> return getServerDefaults();
> }
> Path is ignored ;-)
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