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From André Oriani <aori...@gmail.com>
Subject Re: Heartbeat interval and timeout: why 3 secs and 10 min?
Date Wed, 13 Mar 2013 00:29:09 GMT
No take on this one?

In Zookeeper the heartbeats happen on every third of the timeout.  If I am
not mistaken, recomended timeout is  more than 2 minutes to avoid false

But I still cannot see the relationship on HDFS between heartbeat interval
and timeout. Okay 10 minutes seems to be a conservative value to avoid
false positives in  a big cluster. But that means 200 hearbeats. Heartbeats
on HDFS are not only used for liveness detection but also to send
information about free space and load and to receive commands from
NameNode. So they are also essential for block placement decisions and for
ensuring the replication levels. Would that then be reason why heartbeats
are so frequent? A lot can happen to a DataNode in just three seconds?

André Oriani

On Thu, Mar 7, 2013 at 10:37 PM, André Oriani <aoriani@gmail.com> wrote:

> Hi,
> Is there any particular reason why the default heartbeat interval is 3
> seconds and the timeout is 10 minutes? Everywhere I looked (code, Google,
> ..) only mentions  the values but no clue on why those values were chosen.
> Thanks in advance,
> André Oriani

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