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From "Qian, Ling" <larryq...@gmail.com>
Subject Re: Re: What is the impact on RegionServer Crash?
Date Mon, 13 Oct 2008 14:47:39 GMT
Stack,

  Thanks for your explanations!


2008-10-13 



Qian, Ling 



发件人: stack 
发送时间: 2008-10-11  12:07:42 
收件人: hbase-user@hadoop.apache.org 
抄送: 
主题: Re: What is the impact on RegionServer Crash? 
 
larryqian wrote:
> Dear All,
>
>    During a data query or any of the data operation, if the coresponding Region Server
crashes, will the query continue to work on another Region Server? Or the query fails and
return error to Application?
>   
Depends. Recovery from crash may take some time; a second or two and
even up to minutes if the crashed server was carrying catalog table
regions. Client may time out in the meantime. If the region the query
goes against comes back on line promptly, then client will return query
results as though the crash had not happend.
>    If a free Region Server crashes, the master will find and reschdule the assigned task
after 1 hearbeat, right?
>   
Its all configurable but no, not after one heartbeat. Heartbeats are
every couple of seconds.
<property>
<name>hbase.regionserver.msginterval</name>
<value>3000</value>
<description>Interval between messages from the RegionServer to HMaster
in milliseconds. Default is 3 seconds.
</description>
</property>
Master will consider regionserver dead only after the regionservers'
lease expires in the master. This is the below configuration:
<property>
<name>hbase.master.lease.period</name>
<value>120000</value>
<description>HMaster server lease period in milliseconds. Default is
120 seconds. Region servers must report in within this period else
they are considered dead. On loaded cluster, may need to up this
period.</description>
</property>
St.Ack
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