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https://issues.apache.org/jira/browse/HDFS-17205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17769754#comment-17769754
]
ASF GitHub Bot commented on HDFS-17205:
---------------------------------------
ayushtkn commented on code in PR #6112:
URL: https://github.com/apache/hadoop/pull/6112#discussion_r1339106383
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/HdfsServerConstants.java:
##########
@@ -42,6 +42,7 @@
@InterfaceAudience.Private
public interface HdfsServerConstants {
+ // Will set by {@code
DFSConfigKeys.DFS_NAMENODE_BLOCKPLACEMENTPOLICY_MIN_BLOCKS_FOR_WRITE_KEY}.
Review Comment:
nit
`` Will be set by```
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNode.java:
##########
@@ -2671,6 +2676,18 @@ private String
reconfigureDecommissionBackoffMonitorParameters(
}
}
+ private String reconfigureMinBlocksForWrite(String property, String newValue)
+ throws ReconfigurationException {
+ try {
+ int newSetting = adjustNewVal(
+ DFS_NAMENODE_BLOCKPLACEMENTPOLICY_MIN_BLOCKS_FOR_WRITE_DEFAULT,
newValue);
+ this.namesystem.getBlockManager().setMinBlocksForWrite(newSetting);
Review Comment:
``this.namesystem`` isn't required, can be just
``namesystem.getBlockManager()``?
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java:
##########
@@ -5683,4 +5683,16 @@ public void setExcludeSlowNodesEnabled(boolean enable) {
public boolean getExcludeSlowNodesEnabled(BlockType blockType) {
return placementPolicies.getPolicy(blockType).getExcludeSlowNodesEnabled();
}
+
+ public void setMinBlocksForWrite(int minBlocksForWrite) {
+ ensurePositiveInt(minBlocksForWrite,
+
DFSConfigKeys.DFS_NAMENODE_BLOCKPLACEMENTPOLICY_MIN_BLOCKS_FOR_WRITE_KEY);
Review Comment:
nit
``` DFSConfigKeys.``` isn't required actually there is a static import on
top
```
L20: import static org.apache.hadoop.hdfs.DFSConfigKeys.*;
```
> HdfsServerConstants.MIN_BLOCKS_FOR_WRITE should be configurable
> ---------------------------------------------------------------
>
> Key: HDFS-17205
> URL: https://issues.apache.org/jira/browse/HDFS-17205
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Haiyang Hu
> Assignee: Haiyang Hu
> Priority: Major
> Labels: pull-request-available
>
> Current allocate new block , the NameNode will choose datanode and choose a
> good storage of given storage type from datanode, the specific calling code
> is DatanodeDescriptor#chooseStorage4Block, here will calculate the space
> required for write operations,
> requiredSize = blockSize * HdfsServerConstants.MIN_BLOCKS_FOR_WRITE(default
> is 1).
> {code:java}
> public DatanodeStorageInfo chooseStorage4Block(StorageType t,
> long blockSize) {
> final long requiredSize =
> blockSize * HdfsServerConstants.MIN_BLOCKS_FOR_WRITE;
> final long scheduledSize = blockSize * getBlocksScheduled(t);
> long remaining = 0;
> DatanodeStorageInfo storage = null;
> for (DatanodeStorageInfo s : getStorageInfos()) {
> if (s.getState() == State.NORMAL && s.getStorageType() == t) {
> if (storage == null) {
> storage = s;
> }
> long r = s.getRemaining();
> if (r >= requiredSize) {
> remaining += r;
> }
> }
> }
> if (requiredSize > remaining - scheduledSize) {
> BlockPlacementPolicy.LOG.debug(
> "The node {} does not have enough {} space (required={},"
> + " scheduled={}, remaining={}).",
> this, t, requiredSize, scheduledSize, remaining);
> return null;
> }
> return storage;
> }
> {code}
> But when multiple NameSpaces select the storage of the same datanode to write
> blocks at the same time.
> In extreme cases, if there is only one block size left in the current
> storage, there will be a situation where there is not enough free space for
> the writer to write data.
> log similar to the following appears:
> {code:java}
> The volume [file:/disk1/] with the available space (=21129618 B) is less than
> the block size (=268435456 B).
> {code}
> In order to avoid this case, consider
> HdfsServerConstants.MIN_BLOCKS_FOR_WRITE should be configurable, and the
> parameters can be adjusted in larger clusters.
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