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Hadoop, mail # user - Re: Throttle replication speed in case of datanode failure


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Re: Throttle replication speed in case of datanode failure
Harsh J 2013-01-17, 21:51
One reason (for spikes) may be that the throttler actually runs
periodically (instead of controlling the rate at source, we detect and
block work if we exceed limits, at regular intervals). However, this period
is pretty short so it generally does not cause any ill effects on the
cluster.
On Fri, Jan 18, 2013 at 3:14 AM, Brennon Church <[EMAIL PROTECTED]> wrote:

>  Pretty spiky.  I'll throttle it back to 1MB/s and see if it reduces
> things as expected.
>
> Thanks!
>
> --Brennon
>
>
> On 1/17/13 1:41 PM, Harsh J wrote:
>
> Not true per the sources, it controls all DN->DN copy/move rates, although
> the property name is misleading. Are you noticing a consistent rise in the
> rate or is it spiky?
>
>
> On Fri, Jan 18, 2013 at 2:20 AM, Brennon Church <[EMAIL PROTECTED]>wrote:
>
>>  That doesn't seem to work for under-replicated blocks such as when
>> decommissioning (or losing) a node, just for the balancer.  I've got mine
>> currently set to 10MB/s, but am seeing rates of 3-4 times that after
>> decommissioning a node while it works on bringing things back up to the
>> proper replication factor.
>>
>> Thanks.
>>
>> --Brennon
>>
>>
>> On 1/17/13 11:04 AM, Harsh J wrote:
>>
>> You can limit the bandwidth in bytes/second values applied
>> via dfs.balance.bandwidthPerSec in each DN's hdfs-site.xml. Default is 1
>> MB/s (1048576).
>>
>>  Also, unsure if your version already has it, but it can be applied at
>> runtime too via the dfsadmin -setBalancerBandwidth command.
>>
>>
>> On Thu, Jan 17, 2013 at 8:11 PM, Brennon Church <[EMAIL PROTECTED]>wrote:
>>
>>> Hello,
>>>
>>>  Is there a way to throttle the speed at which under-replicated blocks
>>> are copied across a cluster?  Either limiting the bandwidth or the number
>>> of blocks per time period would work.
>>>
>>>  I'm currently running Hadoop v1.0.1.  I think the
>>> dfs.namenode.replication.work.multiplier.per.iteration option would do the
>>> trick, but that is in v1.1.0 and higher.
>>>
>>>  Thanks.
>>>
>>>  --Brennon
>>>
>>
>>
>>
>>  --
>> Harsh J
>>
>>
>>
>
>
>  --
> Harsh J
>
>
>
--
Harsh J