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https://issues.apache.org/jira/browse/HDFS-14491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16864789#comment-16864789
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Wei-Chiu Chuang commented on HDFS-14491:
----------------------------------------
I'm not sure about this one.
Looking at the code, we doesn't count replica numbers. It counts the unique
blocks.
{code}
/**
* Add a block to the block collection which will be
* invalidated on the specified datanode.
*/
synchronized void add(final Block block, final DatanodeInfo datanode,
final boolean log) {
LightWeightHashSet<Block> set = getBlocksSet(datanode, block);
if (set == null) {
set = new LightWeightHashSet<>();
putBlocksSet(datanode, block, set);
}
if (set.add(block)) {
if (blockIdManager.isStripedBlock(block)) {
numECBlocks.increment();
} else {
numBlocks.increment();
}
if (log) {
NameNode.blockStateChangeLog.debug("BLOCK* {}: add {} to {}",
getClass().getSimpleName(), block, datanode);
}
}
}
{code}
> More Clarity on Namenode UI Around Blocks and Replicas
> ------------------------------------------------------
>
> Key: HDFS-14491
> URL: https://issues.apache.org/jira/browse/HDFS-14491
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Alan Jackoway
> Assignee: Siyao Meng
> Priority: Minor
> Attachments: HDFS-14491.001.patch
>
>
> I recently deleted more than 1/3 of the files in my HDFS installation. During
> the process of the delete, I noticed that the NameNode UI near the top has a
> line like this:
> {quote}44,031,342 files and directories, 38,988,775 blocks = 83,020,117 total
> filesystem object(s).
> {quote}
> Then lower down had a line like this:
> {quote}Number of Blocks Pending Deletion 40000000
> {quote}
> That made it appear that I was deleting more blocks than exist in the
> cluster. When that number was below the total number of blocks, I briefly
> believed I had deleted the entire cluster. In reality, the second number
> includes replicas, while the first does not.
> The UI should be clarified to indicate where "Blocks" includes replicas and
> where it doesn't. This may also have an impact on the under-replicated count.
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