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From Henry Junyoung Kim <henry.jy...@gmail.com>
Subject Re: are we able to decommission multi nodes at one time?
Date Wed, 03 Apr 2013 01:43:38 GMT
@Harsh

What's the reasons to make big gaps for removing nodes between decommission and just down
nodes?
In my understanding, both are necessary to copy un-replicated blocks to another alive nodes.
If main costs of  them are this one, total elapsed time couldn't be big different.

Could you share some articles or documents to understand about decommissioning procedures?
- explaining is always thanks ;)


2013. 4. 2., 오후 5:37, Harsh J <harsh@cloudera.com> 작성:

> Yes, you can do the downtime work in steps of 2 DNs at a time,
> especially since you mentioned the total work would be only ~30mins at
> most.
> 
> On Tue, Apr 2, 2013 at 1:46 PM, Henry Junyoung Kim
> <henry.jykim@gmail.com> wrote:
>> the rest of nodes to be alive has enough size to store.
>> 
>> for this one that you've mentioned.
>>> its easier to do so in a rolling manner without need of a
>>> decommission.
>> 
>> to check my understanding, just shutting down 2 of them and then 2 more and then
2 more without decommissions.
>> 
>> is this correct?
>> 
>> 
>> 2013. 4. 2., 오후 4:54, Harsh J <harsh@cloudera.com> 작성:
>> 
>>> Note though that its only possible to decommission 7 nodes at the same
>>> time and expect it to finish iff the remaining 8 nodes have adequate
>>> free space for the excess replicas.
>>> 
>>> If you're just going to take them down for a short while (few mins
>>> each), its easier to do so in a rolling manner without need of a
>>> decommission. You can take upto two down at a time on a replication
>>> average of 3 or 3+, and put it back in later without too much data
>>> movement impact.
>>> 
>>> On Tue, Apr 2, 2013 at 1:06 PM, Yanbo Liang <yanbohappy@gmail.com> wrote:
>>>> It's reasonable to decommission 7 nodes at the same time.
>>>> But may be it also takes long time to finish it.
>>>> Because all the replicas in these 7 nodes need to be copied to remaining
8
>>>> nodes.
>>>> The size of transfer from these nodes to the remaining nodes is equal.
>>>> 
>>>> 
>>>> 2013/4/2 Henry Junyoung Kim <henry.jykim@gmail.com>
>>>>> 
>>>>> :)
>>>>> 
>>>>> currently, I  have 15 data nodes.
>>>>> for some tests, I am trying to decommission until 8 nodes.
>>>>> 
>>>>> Now, the total dfs used size is 52 TB which is including all replicated
>>>>> blocks.
>>>>> from 15 to 8, total spent time is almost 4 days long. ;(
>>>>> 
>>>>> someone mentioned that I don't need to decommission node by node.
>>>>> for this case, is there no problems if I decommissioned 7 nodes at the
>>>>> same time?
>>>>> 
>>>>> 
>>>>> 2013. 4. 2., 오후 12:14, Azuryy Yu <azuryyyu@gmail.com> 작성:
>>>>> 
>>>>> I can translate it to native English: how many nodes you want to
>>>>> decommission?
>>>>> 
>>>>> 
>>>>> On Tue, Apr 2, 2013 at 11:01 AM, Yanbo Liang <yanbohappy@gmail.com>
wrote:
>>>>>> 
>>>>>> You want to decommission how many nodes?
>>>>>> 
>>>>>> 
>>>>>> 2013/4/2 Henry JunYoung KIM <henry.jykim@gmail.com>
>>>>>>> 
>>>>>>> 15 for datanodes and 3 for replication factor.
>>>>>>> 
>>>>>>> 2013. 4. 1., 오후 3:23, varun kumar <varun.uid@gmail.com>
작성:
>>>>>>> 
>>>>>>>> How many nodes do you have and replication factor for it.
>>>>>>> 
>>>>>> 
>>>>> 
>>>>> 
>>>> 
>>> 
>>> 
>>> 
>>> --
>>> Harsh J
>> 
> 
> 
> 
> -- 
> Harsh J


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