hadoop-hdfs-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Yu Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9666) Enable hdfs-client to read even remote SSD/RAM prior to local disk replica to improve random read
Date Thu, 21 Jan 2016 07:07:39 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9666?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15110188#comment-15110188
] 

Yu Li commented on HDFS-9666:
-----------------------------

bq. However it looked like the benefits of reading from remote RAM were canceled by the RPC
overhead, as compared to short-circuit reads from local disk
Agreed this is true for most *common* case. However, since SATA has much poor io performance
than SSD/RAM, reading from remote SSD/RAM is useful to reduce spike in the system, or say
it's good for reducing the Max latency rather than Avg. And since there's a switch to turn
on/off the feature, user could choose to use it or not according to different scenarios.

> Enable hdfs-client to read even remote SSD/RAM prior to local disk replica to improve
random read
> -------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-9666
>                 URL: https://issues.apache.org/jira/browse/HDFS-9666
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: hdfs-client
>    Affects Versions: 2.6.0, 2.7.0
>            Reporter: ade
>            Assignee: ade
>             Fix For: 2.7.2
>
>         Attachments: HDFS-9666.0.patch
>
>
> We want to improve random read performance of HDFS for HBase, so enabled the heterogeneous
storage in our cluster. But there are only ~50% of datanode & regionserver hosts with
SSD. we can set hfile with only ONE_SSD not ALL_SSD storagepolicy and the regionserver on
none-SSD host can only read the local disk replica . So we developed this feature in hdfs
client to read even remote SSD/RAM prior to local disk replica.



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

Mime
View raw message