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Subject: Re: are we able to decommission multi nodes at one time?
From: Henry Junyoung Kim <henry.jykim@gmail.com>
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Date: Tue, 2 Apr 2013 17:16:58 +0900
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To: user@hadoop.apache.org

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., =BF=C0=C8=C4 4:54, Harsh J <harsh@cloudera.com> =C0=DB=BC=BA:=


> 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.
>=20
> 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.
>=20
> 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.
>>=20
>>=20
>> 2013/4/2 Henry Junyoung Kim <henry.jykim@gmail.com>
>>>=20
>>> :)
>>>=20
>>> currently, I  have 15 data nodes.
>>> for some tests, I am trying to decommission until 8 nodes.
>>>=20
>>> 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. ;(
>>>=20
>>> 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?
>>>=20
>>>=20
>>> 2013. 4. 2., =BF=C0=C8=C4 12:14, Azuryy Yu <azuryyyu@gmail.com> =
=C0=DB=BC=BA:
>>>=20
>>> I can translate it to native English: how many nodes you want to
>>> decommission?
>>>=20
>>>=20
>>> On Tue, Apr 2, 2013 at 11:01 AM, Yanbo Liang <yanbohappy@gmail.com> =
wrote:
>>>>=20
>>>> You want to decommission how many nodes?
>>>>=20
>>>>=20
>>>> 2013/4/2 Henry JunYoung KIM <henry.jykim@gmail.com>
>>>>>=20
>>>>> 15 for datanodes and 3 for replication factor.
>>>>>=20
>>>>> 2013. 4. 1., =BF=C0=C8=C4 3:23, varun kumar <varun.uid@gmail.com> =
=C0=DB=BC=BA:
>>>>>=20
>>>>>> How many nodes do you have and replication factor for it.
>>>>>=20
>>>>=20
>>>=20
>>>=20
>>=20
>=20
>=20
>=20
> --=20
> Harsh J