[
https://issues.apache.org/jira/browse/HDFS-7661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15229490#comment-15229490
]
Todd Lipcon commented on HDFS-7661:
-----------------------------------
I'm not super active on either HDFS or HBase anymore, but Kai asked me to take
a look at the issue, especially with regard to his latest comment. My (slightly
ill-informed) opinion is that he's right -- this sounds like a very complicated
feature to get right, and maybe has minimal benefit. For HBase, the use case
for hflush is for the WALs, which typically make up a vast minority of the disk
space usage of the cluster. So, the benefits of EC from a space-savings
perspective are not so large. The benefits from a throughput perspective due to
striping sound enticing at first, but I think it's probably better addressed by
the "multi-WAL" feature which already allows striping at the application level.
So, my gut feel is that for the first EC-supporting release it might be safest
to not include the feature, or to do so only as an experimental feature that
has to be enabled by a config (somewhat like dfs.support.append was, way back
in the day when it wasnt super stable).
> [umbrella] support hflush and hsync for erasure coded files
> -----------------------------------------------------------
>
> Key: HDFS-7661
> URL: https://issues.apache.org/jira/browse/HDFS-7661
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: erasure-coding
> Reporter: Tsz Wo Nicholas Sze
> Assignee: GAO Rui
> Attachments: EC-file-flush-and-sync-steps-plan-2015-12-01.png,
> HDFS-7661-unitTest-wip-trunk.patch, HDFS-7661-wip.01.patch,
> HDFS-EC-file-flush-sync-design-v20160323.pdf,
> HDFS-EC-file-flush-sync-design-version1.1.pdf, Undo-Log-Design-20160406.jpg
>
>
> We also need to support hflush/hsync and visible length.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
