hadoop-hdfs-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Andrew Wang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-3702) Add an option for NOT writing the blocks locally if there is a datanode on the same box as the client
Date Wed, 16 Mar 2016 22:19:33 GMT

    [ https://issues.apache.org/jira/browse/HDFS-3702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15198302#comment-15198302
] 

Andrew Wang commented on HDFS-3702:
-----------------------------------

Hi Arpit,

We've got +1's from HBase developers like Stack and Nicolas, so from that perspective it sounds
like they approve of the API in this patch (your "churn" concern?). Could you elaborate about
your concern about adding more placement hints in the future? Since there's the flags enumset,
it seems like we can keep using more flags for additional hints. Stack/nkeywal can comment
more, but I think this is also one of their biggest block placement requests besides co-location
of HFiles for a region, which will be a big effort for both of our projects.

> Add an option for NOT writing the blocks locally if there is a datanode on the same box
as the client
> -----------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-3702
>                 URL: https://issues.apache.org/jira/browse/HDFS-3702
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: hdfs-client
>    Affects Versions: 2.5.1
>            Reporter: Nicolas Liochon
>            Assignee: Lei (Eddy) Xu
>            Priority: Minor
>              Labels: BB2015-05-TBR
>         Attachments: HDFS-3702.000.patch, HDFS-3702.001.patch, HDFS-3702.002.patch, HDFS-3702.003.patch,
HDFS-3702.004.patch, HDFS-3702.005.patch, HDFS-3702.006.patch, HDFS-3702.007.patch, HDFS-3702.008.patch,
HDFS-3702_Design.pdf
>
>
> This is useful for Write-Ahead-Logs: these files are writen for recovery only, and are
not read when there are no failures.
> Taking HBase as an example, these files will be read only if the process that wrote them
(the 'HBase regionserver') dies. This will likely come from a hardware failure, hence the
corresponding datanode will be dead as well. So we're writing 3 replicas, but in reality only
2 of them are really useful.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message