hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Hairong Kuang (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-1652) Rebalance data blocks when new data nodes added or data nodes become full
Date Wed, 22 Aug 2007 21:10:30 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-1652?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Hairong Kuang updated HADOOP-1652:

    Attachment: RebalanceDesign5.pdf

Attached is a new version of the design document which includes the following changes:
1. A block is pulled by a destination instead of pushed from a source.
2. A block can be pulled from a proxy source which contains the block and is closer to the
destination or less loaded than the source.
3. A source does not delete a block by itself. Instead a destination notifies the name node
that a block is copied and a hint that a replica at the source should be removed if the block
is over replicated. When the name node decides to remove an excessive replica, it favors the
hint as long as doing so does not violate the rebalancing requirement 1. A source removes
the block upon a request from the name node.

> Rebalance data blocks when new data nodes added or data nodes become full
> -------------------------------------------------------------------------
>                 Key: HADOOP-1652
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1652
>             Project: Hadoop
>          Issue Type: New Feature
>          Components: dfs
>    Affects Versions: 0.13.0
>            Reporter: Hairong Kuang
>            Assignee: Hairong Kuang
>             Fix For: 0.15.0
>         Attachments: RebalanceDesign4.pdf, RebalanceDesign5.pdf
> When a new data node joins hdfs cluster, it does not hold much data. So any map task
assigned to the machine most likely does not read local data, thus increasing the use of network
bandwidth. On the other hand, when some data nodes become full, new data blocks are placed
on only non-full data nodes, thus reducing their read parallelism. 
> This jira aims to find an approach to redistribute data blocks when imbalance occurs
in the cluster.  An solution should meet the following requirements:
> 1. It maintains data availablility guranteens in the sense that rebalancing does not
reduce the number of replicas that a block has or the number of racks that the block resides.
> 2. An adminstrator should be able to invoke and interrupt rebalancing from a command
> 3. Rebalancing should be throttled so that rebalancing does not cause a namenode to be
too busy to serve any incoming request or saturate the network.

This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

View raw message