[
https://issues.apache.org/jira/browse/HDFS-6524?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16950270#comment-16950270
]
Ayush Saxena commented on HDFS-6524:
------------------------------------
I am sorry, I think I have got little confused, but if I see the variable
{{failures}}, it says :
{code:java}
* Specifically this counts the number of times the client has gone
* back to the namenode to get a new list of block locations, and is
* capped at maxBlockAcquireFailures
*/
protected int failures = 0;
{code}
It is to denote the number of times the client went back to get the block
locations from the namenode, Means to cover if the blocks have got moved, to
get the new block locations. How it is related to number of replicas?
If say number of replica is 1 and if the blocks got moved the client won't
retry to namenode for getting the new location, and in first try only it will
throw exception.
> Choosing datanode retries times considering with block replica number
> ----------------------------------------------------------------------
>
> Key: HDFS-6524
> URL: https://issues.apache.org/jira/browse/HDFS-6524
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client
> Affects Versions: 3.0.0-alpha1
> Reporter: Liang Xie
> Assignee: Lisheng Sun
> Priority: Minor
> Labels: BB2015-05-TBR
> Attachments: HDFS-6524.001.patch, HDFS-6524.002.patch,
> HDFS-6524.003.patch, HDFS-6524.004.patch, HDFS-6524.005(2).patch,
> HDFS-6524.005.patch, HDFS-6524.006.patch, HDFS-6524.007.patch, HDFS-6524.txt
>
>
> Currently the chooseDataNode() does retry with the setting:
> dfsClientConf.maxBlockAcquireFailures, which by default is 3
> (DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_DEFAULT = 3), it would be better
> having another option, block replication factor. One cluster with only two
> block replica setting, or using Reed-solomon encoding solution with one
> replica factor. It helps to reduce the long tail latency.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org
