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From "Keith Turner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-683) Accumulo ignores HDFS max replication configuration
Date Wed, 11 Jul 2012 17:25:35 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-683?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13411743#comment-13411743
] 

Keith Turner commented on ACCUMULO-683:
---------------------------------------

One concern I have about issues like this is for indirect users of Accumulo.  An indirect
user of Accumulo is someone who is using something like OpenTSDB[1] or Jaccson[2].   These
users  want to know as little about Accumuo as possible, they just want OpenTSDB or Jaccson
to work.  For these users, the assumption that setting a config option on the metadata table
is a trivial operation does not hold.  It could take them a while to figure out what they
need to do to fix this issue.  

This issue is somewhat similar to the java policy file that could keep Accumulo from running
and make users spend a lot of time figuring it out.  The issue differs in that its much less
likely and increases the probability of loss of critical data.  It changes probabilities,
but it does not make data loss certain.

Also I think if a user sets max replication, they mean it.  I think Accumulo should just work
(automatically take the min setting) and log a warning.

Basically I am in favor of Accumulo just working in as many situations as possible.

Also, setting the metadata table replication to 5 instead of 3 was something I did w/o much
thought when adding per table replication setting.  The basic premise what that 5 is better
than 3.  I certainly did not analyze the probabilities of how it affects your odds under different
datanode loss situations.  For example instead of being 5, should it be some function of the
cluster size? I dunno know.

We will probably also run into a similar issue if someone sets the min hdfs replication >
5.  We should handle that issue in this ticket also.


[1] : https://github.com/ericnewton/opentsdb
[2] : https://github.com/acordova/jaccson

John, I like your suggestion about checking in when the user runs init and prompting.  The
prompt should suggest a default that will work.


                
> Accumulo ignores HDFS max replication configuration
> ---------------------------------------------------
>
>                 Key: ACCUMULO-683
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-683
>             Project: Accumulo
>          Issue Type: Bug
>          Components: tserver
>    Affects Versions: 1.4.1
>            Reporter: Jim Klucar
>            Assignee: Keith Turner
>            Priority: Minor
>
> I setup a new 1.4.1 instance that was running on top of a Hadoop installation that had
the maximum block replications set to 3 and the following error showed up on the monitor page.
> java.io.IOException: failed to create file /accumulo/tables/!0/table_info/F0000001.rf_tmp
on client 127.0.0.1. Requested replication 5 exceeds maximum 3 at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:1220)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFile(FSNamesystem.java:1123) at
org.apache.hadoop.hdfs.server.namenode.NameNode.create(NameNode.java:551) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native
Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:523) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1383)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1379) at java.security.AccessController.doPrivileged(Native
Method) at javax.security.auth.Subject.doAs(Subject.java:396) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1377)
> Tablet server error is:
> 10 10:56:25,408 [tabletserver.MinorCompactor] WARN : MinC failed (java.io.IOException:
failed to create file /accumulo/tables/!0/
> table_info/F0000001.rf_tmp on client 127.0.0.1.
> Requested replication 5 exceeds maximum 3
>         at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:1220)
>         at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFile(FSNamesystem.java:1123)
>         at org.apache.hadoop.hdfs.server.namenode.NameNode.create(NameNode.java:551)
>         at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>         at java.lang.reflect.Method.invoke(Method.java:597)
>         at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:523)
>         at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1383)
>         at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1379)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at javax.security.auth.Subject.doAs(Subject.java:396)
>         at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
>         at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1377)
> ) to create /accumulo/tables/!0/table_info/F0000001.rf_tmp retrying ...

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