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From Chackravarthy Esakkimuthu <chaku.mi...@gmail.com>
Subject Re: HDFS HA(Based on QJM) Failover Frequently with Large FSimage and Busy Requests
Date Wed, 26 Apr 2017 09:49:36 GMT
1. Is service-rpc configured in namenode?

(dfs.namenode.servicerpc-address - this will create another RPC server
listening on another port (say 8021) to handle all service (non-client)
requests and hence default rpc address (say 8020) will handle only client
requests.)

By doing this way, you would be able to decouple client and service
requests. Here service requests corresponds to rpc calls from DN, ZKFC etc.
Hence when cluster is too busy because of too many client operations, ZKFC
requests will get processed by different rpc and hence need not wait in
same queue as client requests.)

2. ha.health-monitor.rpc-timeout.ms - Also consider increasing zkfc rpc
call timeout to namenode.

By default this is 45 secs. You can consider increasing it to 1 or 2 mins
depending upon your cluster usage.

Thanks,
Chackra

On Wed, Apr 26, 2017 at 11:50 AM, <gu.yizhou@zte.com.cn> wrote:

>
> *Hi All,*
>
>     HDFS HA (Based on QJM) , 5 journalnodes, Apache 2.5.0 on Redhat 6.5
> with JDK1.7.
>
>     Put 1P+ data into HDFS with FSimage about 10G, then keep on making
> more requests to this HDFS, namenodes failover frequently. Wanna to know
> something as follows:
>
>
>  *   1.ANN(active namenode) downloading fsimage.ckpt_* from SNN(standby
> namenode) leads to very high disk io, at the same time, zkfc fails to
> monitor the health of ann due to timeout. Is there any releationship
> between high disk io and zkfc monitor request timeout? Every failover
> happened when ckpt download, but not every ckpt download leads to failover.*
>
>
>
> 2017-03-15 09:27:05,750 WARN org.apache.hadoop.ha.HealthMonitor:
> Transport-level exception trying to monitor health of NameNode at
> nn1/ip:8020: Call From nn1/ip to nn1:8020 failed on socket timeout
> exception: java.net.SocketTimeoutException: 45000 millis timeout while
> waiting for channel to be ready for read. ch : java.nio.channels.SocketChannel[connected
> local=/ip:48536 remote=nn1/ip:8020]; For more details see:
> http://wiki.apache.org/hadoop/SocketTimeout
>
> 2017-03-15 09:27:05,750 INFO org.apache.hadoop.ha.HealthMonitor: Entering
> state SERVICE_NOT_RESPONDING
>
>
> *    2.Due to SERVICE_NOT_RESPONDING, another zkfc fences the old
> ann(configed sshfence), before restart by my additional monitor, old ann
> log sometimes shows like this, what is "Rescan of
> postponedMisreplicatedBlocks"? Does this have any reletionships with
> failover?*
>
> 2017-03-15 04:36:00,866 INFO org.apache.hadoop.hdfs.server.
> blockmanagement.CacheReplicationMonitor: Rescanning after 30000
> milliseconds
>
> 2017-03-15 04:36:00,931 INFO org.apache.hadoop.hdfs.server.
> blockmanagement.CacheReplicationMonitor: Scanned 0 directive(s) and 0
> block(s) in 65 millisecond(s).
>
> 2017-03-15 04:36:01,127 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager:
> Rescan of postponedMisreplicatedBlocks completed in 23 msecs. 247361 blocks
> are left. 0 blocks are removed.
>
> 2017-03-15 04:36:04,145 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager:
> Rescan of postponedMisreplicatedBlocks completed in 17 msecs. 247361 blocks
> are left. 0 blocks are removed.
>
> 2017-03-15 04:36:07,159 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager:
> Rescan of postponedMisreplicatedBlocks completed in 14 msecs. 247361 blocks
> are left. 0 blocks are removed.
>
> 2017-03-15 04:36:10,173 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager:
> Rescan of postponedMisreplicatedBlocks completed in 14 msecs. 247361 blocks
> are left. 0 blocks are removed.
>
> 2017-03-15 04:36:13,188 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager:
> Rescan of postponedMisreplicatedBlocks completed in 14 msecs. 247361 blocks
> are left. 0 blocks are removed.
>
> 2017-03-15 04:36:16,211 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager:
> Rescan of postponedMisreplicatedBlocks completed in 23 msecs. 247361 blocks
> are left. 0 blocks are removed.
>
> 2017-03-15 04:36:19,234 INFO org.apache.hadoop.hdfs.server.blockmanagement.BlockManager:
> Rescan of postponedMisreplicatedBlocks completed in 22 msecs. 247361 blocks
> are left. 0 blocks are removed.
>
> 2017-03-15 04:36:28,994 INFO org.apache.hadoop.hdfs.server.namenode.NameNode:
> STARTUP_MSG:
>
>
>     *3.I config two dfs.namenode.name.dir and
> one dfs.journalnode.edits.dir(which shares one disk with nn), is it
> suitable? Or does this have any disadvantage?*
>
>
> <property>
>
> <name>dfs.namenode.name.dir.nameservice.nn1</name>
>
> <value>/data1/hdfs/dfs/name,/data2/hdfs/dfs/name</value>
>
> </property>
>
> <property>
>
> <name>dfs.namenode.name.dir.nameservice.nn2</name>
>
> <value>/data1/hdfs/dfs/name,/data2/hdfs/dfs/name</value>
>
> </property>
>
>
> <property>
>
> <name>dfs.journalnode.edits.dir</name>
>
> <value>/data1/hdfs/dfs/journal</value>
>
> </property>
>
>
>
>    * 4.Interested in design of checkpoint and edit logs transmission,any
> explanation,issues or documents?*
>
>
> *Thanks in advance,*
>
> *Doris*
>
>
>
>
>
>
>
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