[
http://issues.apache.org/jira/browse/HADOOP-692?page=comments#action_12448893 ]
Doug Cutting commented on HADOOP-692:
-------------------------------------
How about a topology interface?
public interface NetworkTopology {
HubDistance[] getHubDistances(String host)
}
public interface HubDistance {
public String getHubName();
public int getHops();
}
The namenode can use this to refresh things dynamically, or it might be read
statically from a config file, depending on the implementation. The
implementation class can be specified in the config. The default could just
chop up hostnames, so that foo.bar.co.uk yeilds hops <foo.bar.co.uk,0>,
<bar.co.uk,2>, <co.uk,3>, <uk,4>. Someone could implement this with DNS too.
To compute a distance, you find the common hub between two nodes and sum the
hops. To find nearby nodes, look for nodes sharing a nearby hub. Etc.
> Rack-aware Replica Placement
> ----------------------------
>
> Key: HADOOP-692
> URL: http://issues.apache.org/jira/browse/HADOOP-692
> Project: Hadoop
> Issue Type: Improvement
> Components: dfs
> Affects Versions: 0.8.0
> Reporter: Hairong Kuang
> Assigned To: Hairong Kuang
> Fix For: 0.9.0
>
>
> This issue assumes that HDFS runs on a cluster of computers that spread
> across many racks. Communication between two nodes on different racks needs
> to go through switches. Bandwidth in/out of a rack may be less than the total
> bandwidth of machines in the rack. The purpose of rack-aware replica
> placement is to improve data reliability, availability, and network bandwidth
> utilization. The basic idea is that each data node determines to which rack
> it belongs at the startup time and notifies the name node of the rack id upon
> registration. The name node maintains a rackid-to-datanode map and tries to
> place replicas across racks.
--
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators:
http://issues.apache.org/jira/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
