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Posted to user@cassandra.apache.org by Jens Rantil <je...@tink.se> on 2015/06/05 14:15:16 UTC
Decommission datacenter - repair?
Hi,
I asked this on IRC earlier today, but didn't get any response;
Datastax's documentation on "Decommissioning a data center
<http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_decomission_dc_t.html>"
tells me to run a full repair and then decommission each node. Isn't
decommissioning going to hand over all data anyway? Then why is the repair
necessary?
Cheers,
Jens
--
Jens Rantil
Backend engineer
Tink AB
Email: jens.rantil@tink.se
Phone: +46 708 84 18 32
Web: www.tink.se
Facebook <https://www.facebook.com/#!/tink.se> Linkedin
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Twitter <https://twitter.com/tink>
Re: Decommission datacenter - repair?
Posted by Jens Rantil <je...@tink.se>.
Ah, that explains things. Thanks!
On Fri, Jun 5, 2015 at 10:59 PM, Robert Coli <rc...@eventbrite.com> wrote:
> On Fri, Jun 5, 2015 at 5:15 AM, Jens Rantil <je...@tink.se> wrote:
>
>> Datastax's documentation on "Decommissioning a data center
>> <http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_decomission_dc_t.html>"
>> tells me to run a full repair and then decommission each node. Isn't
>> decommissioning going to hand over all data anyway? Then why is the repair
>> necessary?
>>
>
> In step 3 of those instructions you reduce the number of replicas in the
> departing DC to 0.
>
> The departing DC no longer owns ranges at this point, and no longer is
> responsible for replicas.
>
> It therefore does no streaming (except maybe hints?) when you decommission
> nodes.
>
> =Rob
>
>
>
--
Jens Rantil
Backend engineer
Tink AB
Email: jens.rantil@tink.se
Phone: +46 708 84 18 32
Web: www.tink.se
Facebook <https://www.facebook.com/#!/tink.se> Linkedin
<http://www.linkedin.com/company/2735919?trk=vsrp_companies_res_photo&trkInfo=VSRPsearchId%3A1057023381369207406670%2CVSRPtargetId%3A2735919%2CVSRPcmpt%3Aprimary>
Twitter <https://twitter.com/tink>
Re: Decommission datacenter - repair?
Posted by Robert Coli <rc...@eventbrite.com>.
On Fri, Jun 5, 2015 at 5:15 AM, Jens Rantil <je...@tink.se> wrote:
> Datastax's documentation on "Decommissioning a data center
> <http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_decomission_dc_t.html>"
> tells me to run a full repair and then decommission each node. Isn't
> decommissioning going to hand over all data anyway? Then why is the repair
> necessary?
>
In step 3 of those instructions you reduce the number of replicas in the
departing DC to 0.
The departing DC no longer owns ranges at this point, and no longer is
responsible for replicas.
It therefore does no streaming (except maybe hints?) when you decommission
nodes.
=Rob
Re: Decommission datacenter - repair?
Posted by Kiran mk <co...@gmail.com>.
Yes, but will not handover the data to any node, it rather intimates that
other nodes of the replicas so that they rebalance the nodes with the help
of repair.
Best Regards,
Kiran.M.K.
On Jun 5, 2015 6:38 PM, "Jens Rantil" <je...@tink.se> wrote:
> Hi Kiran,
>
> So, am I understanding you correctly that a decommissioning node only will
> hand over its data to a single node? If it would hand it over to all other
> replica nodes, I see that essentially as an implicit repair. Am I wrong?
>
> Thanks,
> Jens
>
> On Fri, Jun 5, 2015 at 2:27 PM, Kiran mk <co...@gmail.com> wrote:
>
>> Hi Jens,
>>
>> If you decommission a data center, The data residing in the Data Center
>> which you are planning for decommission has to be balanced to the nodes of
>> the other data center satisfying RF. Hence Repair is required.
>>
>> Best Regards,
>> Kiran.M.K.
>>
>> On Fri, Jun 5, 2015 at 5:45 PM, Jens Rantil <je...@tink.se> wrote:
>>
>>> Hi,
>>>
>>> I asked this on IRC earlier today, but didn't get any response;
>>>
>>> Datastax's documentation on "Decommissioning a data center
>>> <http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_decomission_dc_t.html>"
>>> tells me to run a full repair and then decommission each node. Isn't
>>> decommissioning going to hand over all data anyway? Then why is the repair
>>> necessary?
>>>
>>> Cheers,
>>> Jens
>>>
>>> --
>>> Jens Rantil
>>> Backend engineer
>>> Tink AB
>>>
>>> Email: jens.rantil@tink.se
>>> Phone: +46 708 84 18 32
>>> Web: www.tink.se
>>>
>>> Facebook <https://www.facebook.com/#!/tink.se> Linkedin
>>> <http://www.linkedin.com/company/2735919?trk=vsrp_companies_res_photo&trkInfo=VSRPsearchId%3A1057023381369207406670%2CVSRPtargetId%3A2735919%2CVSRPcmpt%3Aprimary>
>>> Twitter <https://twitter.com/tink>
>>>
>>
>>
>>
>> --
>> Best Regards,
>> Kiran.M.K.
>>
>
>
>
> --
> Jens Rantil
> Backend engineer
> Tink AB
>
> Email: jens.rantil@tink.se
> Phone: +46 708 84 18 32
> Web: www.tink.se
>
> Facebook <https://www.facebook.com/#!/tink.se> Linkedin
> <http://www.linkedin.com/company/2735919?trk=vsrp_companies_res_photo&trkInfo=VSRPsearchId%3A1057023381369207406670%2CVSRPtargetId%3A2735919%2CVSRPcmpt%3Aprimary>
> Twitter <https://twitter.com/tink>
>
Re: Decommission datacenter - repair?
Posted by Jens Rantil <je...@tink.se>.
Hi Kiran,
So, am I understanding you correctly that a decommissioning node only will
hand over its data to a single node? If it would hand it over to all other
replica nodes, I see that essentially as an implicit repair. Am I wrong?
Thanks,
Jens
On Fri, Jun 5, 2015 at 2:27 PM, Kiran mk <co...@gmail.com> wrote:
> Hi Jens,
>
> If you decommission a data center, The data residing in the Data Center
> which you are planning for decommission has to be balanced to the nodes of
> the other data center satisfying RF. Hence Repair is required.
>
> Best Regards,
> Kiran.M.K.
>
> On Fri, Jun 5, 2015 at 5:45 PM, Jens Rantil <je...@tink.se> wrote:
>
>> Hi,
>>
>> I asked this on IRC earlier today, but didn't get any response;
>>
>> Datastax's documentation on "Decommissioning a data center
>> <http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_decomission_dc_t.html>"
>> tells me to run a full repair and then decommission each node. Isn't
>> decommissioning going to hand over all data anyway? Then why is the repair
>> necessary?
>>
>> Cheers,
>> Jens
>>
>> --
>> Jens Rantil
>> Backend engineer
>> Tink AB
>>
>> Email: jens.rantil@tink.se
>> Phone: +46 708 84 18 32
>> Web: www.tink.se
>>
>> Facebook <https://www.facebook.com/#!/tink.se> Linkedin
>> <http://www.linkedin.com/company/2735919?trk=vsrp_companies_res_photo&trkInfo=VSRPsearchId%3A1057023381369207406670%2CVSRPtargetId%3A2735919%2CVSRPcmpt%3Aprimary>
>> Twitter <https://twitter.com/tink>
>>
>
>
>
> --
> Best Regards,
> Kiran.M.K.
>
--
Jens Rantil
Backend engineer
Tink AB
Email: jens.rantil@tink.se
Phone: +46 708 84 18 32
Web: www.tink.se
Facebook <https://www.facebook.com/#!/tink.se> Linkedin
<http://www.linkedin.com/company/2735919?trk=vsrp_companies_res_photo&trkInfo=VSRPsearchId%3A1057023381369207406670%2CVSRPtargetId%3A2735919%2CVSRPcmpt%3Aprimary>
Twitter <https://twitter.com/tink>
Re: Decommission datacenter - repair?
Posted by Kiran mk <co...@gmail.com>.
Hi Jens,
If you decommission a data center, The data residing in the Data Center
which you are planning for decommission has to be balanced to the nodes of
the other data center satisfying RF. Hence Repair is required.
Best Regards,
Kiran.M.K.
On Fri, Jun 5, 2015 at 5:45 PM, Jens Rantil <je...@tink.se> wrote:
> Hi,
>
> I asked this on IRC earlier today, but didn't get any response;
>
> Datastax's documentation on "Decommissioning a data center
> <http://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_decomission_dc_t.html>"
> tells me to run a full repair and then decommission each node. Isn't
> decommissioning going to hand over all data anyway? Then why is the repair
> necessary?
>
> Cheers,
> Jens
>
> --
> Jens Rantil
> Backend engineer
> Tink AB
>
> Email: jens.rantil@tink.se
> Phone: +46 708 84 18 32
> Web: www.tink.se
>
> Facebook <https://www.facebook.com/#!/tink.se> Linkedin
> <http://www.linkedin.com/company/2735919?trk=vsrp_companies_res_photo&trkInfo=VSRPsearchId%3A1057023381369207406670%2CVSRPtargetId%3A2735919%2CVSRPcmpt%3Aprimary>
> Twitter <https://twitter.com/tink>
>
--
Best Regards,
Kiran.M.K.