[
https://issues.apache.org/jira/browse/ACCUMULO-722?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13469083#comment-13469083
]
Eric Newton commented on ACCUMULO-722:
--------------------------------------
David, I browsed the CFS site. The first question on that page asks about the
tricky part where there's only one writer to a file. This is a key problem,
since having a single writer to a write-ahead-log is key for proper failure
conditions. In particular, we must ensure that the writes by a failing tablet
server to its write-ahead log are denied while we use that file for recovery.
The response "HDFS does not implement posix semantics" is true, but it
understates the importance of this feature to the HBase and/or Accumulo WAL.
And, it appears this is not an open-source solution, so I'm unable to test it
without committing additional resources. Does anyone know if they support
exclusive writer semantics?
> Accumulo using Accumulo as its own NameNode
> -------------------------------------------
>
> Key: ACCUMULO-722
> URL: https://issues.apache.org/jira/browse/ACCUMULO-722
> Project: Accumulo
> Issue Type: Bug
> Reporter: Eric Newton
> Assignee: Eric Newton
>
> On large clusters, the NameNode can become a performance bottleneck. The
> NameNode is also a single-point of failure. Recent improvements to HDFS to
> support High Availability and Federation [See ACCUMULO-118] help address
> these issues, but at greater administrative costs and specialized hardware.
> We have seen demonstrations of using HBase to host a NameNode. There's Aaron
> Cordova's example of a Distributed Name Node:
> [Design for a Distributed Name Node
> |http://www.slideshare.net/acordova00/design-for-a-distributed-name-node ]
> And giraffa:
> [Dynamic Namespace Partitioning with Giraffa File System
> |http://www.slideshare.net/Hadoop_Summit/dynamic-namespace-partitioning-with-giraffa-file-system]
> We could incrementally implement a self-hosted Accumulo, which would run as
> its own NameNode. This would be useful for large Accumulo installations.
> Over the long term, we could incorporate all NameNode functions to provide a
> scalable, distributed NameNode for other large Hadoop installations.
> Hopefully the approach used could be trivially ported to HBase as well.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
