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https://issues.apache.org/jira/browse/HDFS-7994?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487162#comment-14487162
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Hui Zheng commented on HDFS-7994:
---------------------------------
Hi [~szetszwo]
I want to confirm my understanding about this issue.Is it correct?
When the NameNode loads a fsimage,it doesn't care about whether the block is an
EC Block during putting the blocks into the BlocksMap.
But it should take different lookup actions for non-EC/EC blocks during
processing BlockReport.
For non-EC blocks it only does a lookup in the blocksmap by blockid.
For EC blocks it must convert the blockid to EC-Blockid(the blockid of the
first block of a EC block group).
I think the current implementation has complete this function.
{code}
public BlockInfo getStoredBlock(Block block) {
BlockInfo info = null;
if (BlockIdManager.isStripedBlockID(block.getBlockId())) {
info = blocksMap.getStoredBlock(
new Block(BlockIdManager.convertToStripedID(block.getBlockId())));
//AAA
}
if (info == null) {
info = blocksMap.getStoredBlock(block); // BBB
}
return info;
}
{code}
1. A StripedBlockId(whether or not the low 4 bits are not '0000') comes and the
block is really EC block, it can be found by AAA.
2. A StripedBlockId whose low 4 bits are '0000' comes but the block is not EC,
it can also be found by AAA.
3. A StripedBlockId whose low 4 bits are NOT '0000' comes but the block is not
EC, it can be found by BBB.
3. A non-StripedBlockId comes,it can be found by BBB.
So I don't think we need to process this issue.
> Detect if resevered EC Block ID is already used
> -----------------------------------------------
>
> Key: HDFS-7994
> URL: https://issues.apache.org/jira/browse/HDFS-7994
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Tsz Wo Nicholas Sze
> Assignee: Hui Zheng
>
> Since random block IDs were supported by some early version of HDFS, the
> block ID reserved for EC blocks could be already used by some existing blocks
> in a cluster. During NameNode startup, it detects if there are reserved EC
> block IDs used by non-EC blocks. If it is the case, NameNode will do an
> additional blocksMap lookup when there is a miss in a blockGroupsMap lookup.
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