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Posted to user@cassandra.apache.org by jean paul <re...@gmail.com> on 2016/12/18 18:47:19 UTC
All nodes hosting replicas down
Hi,
Please, if we choose a replication factor =2 (simple strategy), so, we have
two replicas of data on the ring.
What happen in the case of all nodes containing replicas are down ?
Thank you so much for help.
Kind regards.
Re: All nodes hosting replicas down
Posted by Ben Slater <be...@instaclustr.com>.
And I’m not aware of any case where it’s a good idea to use SimpleStrategy
in Prod (be interested to hear if anyone else knows of one).
NetworkTopologyStrategy behaves the same as SimpleStrategy in the basic
case of one DC and Rack but gives you a good path to migrate to more
sophisticated topologies in the future. If you run on SimpleStrategy then
any future migration to NetworkTopologyStrategy will be painful.
Cheers
Ben
On Mon, 19 Dec 2016 at 07:30 Benjamin Roth <be...@jaumo.com> wrote:
> For sensitive data, I'd recommend to use at least RF=3. Especially if you
> plan to use CL QUORUM, for example if you want to ensure consistency.
> If you use QUORUM and RF=2 then a single failing node will make your data
> unavailable.
>
> For more information, please read
> https://docs.datastax.com/en/cassandra/2.0/cassandra/dml/dml_config_consistency_c.html
> There are a lot more resources out there that go more into detail when and
> why to use what CL.
>
> 2016-12-18 21:21 GMT+01:00 jean paul <re...@gmail.com>:
>
> Thank you so much for answer.
>
> So, in case of a high failure rate in my cluster, i have to increase the
> replication factor or i have to use NetworkToplogy Strategy ?
> That's it ?
>
> Kindly.
>
>
> 2016-12-18 20:23 GMT+01:00 Matija Gobec <ma...@gmail.com>:
>
> If you are reading and none of the replicas is online you will get an
> exception on the read (tried x replicas but 0 responded) and your read will
> fail. Writes on the other hand are going to go through only if your write
> consistency is ANY. If your write consistency is ONE or anything upwards,
> then it will fail too.
>
> On Sun, Dec 18, 2016 at 7:47 PM, jean paul <re...@gmail.com> wrote:
>
> Hi,
>
> Please, if we choose a replication factor =2 (simple strategy), so, we
> have two replicas of data on the ring.
>
> What happen in the case of all nodes containing replicas are down ?
>
>
> Thank you so much for help.
>
> Kind regards.
>
>
>
>
>
>
> --
> Benjamin Roth
> Prokurist
>
> Jaumo GmbH · www.jaumo.com
> Wehrstraße 46 · 73035 Göppingen · Germany
> Phone +49 7161 304880-6 <+49%207161%203048806> · Fax +49 7161 304880-1
> <+49%207161%203048801>
> AG Ulm · HRB 731058 · Managing Director: Jens Kammerer
>
Re: All nodes hosting replicas down
Posted by Benjamin Roth <be...@jaumo.com>.
For sensitive data, I'd recommend to use at least RF=3. Especially if you
plan to use CL QUORUM, for example if you want to ensure consistency.
If you use QUORUM and RF=2 then a single failing node will make your data
unavailable.
For more information, please read
https://docs.datastax.com/en/cassandra/2.0/cassandra/dml/dml_config_consistency_c.html
There are a lot more resources out there that go more into detail when and
why to use what CL.
2016-12-18 21:21 GMT+01:00 jean paul <re...@gmail.com>:
> Thank you so much for answer.
>
> So, in case of a high failure rate in my cluster, i have to increase the
> replication factor or i have to use NetworkToplogy Strategy ?
> That's it ?
>
> Kindly.
>
>
> 2016-12-18 20:23 GMT+01:00 Matija Gobec <ma...@gmail.com>:
>
>> If you are reading and none of the replicas is online you will get an
>> exception on the read (tried x replicas but 0 responded) and your read will
>> fail. Writes on the other hand are going to go through only if your write
>> consistency is ANY. If your write consistency is ONE or anything upwards,
>> then it will fail too.
>>
>> On Sun, Dec 18, 2016 at 7:47 PM, jean paul <re...@gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> Please, if we choose a replication factor =2 (simple strategy), so, we
>>> have two replicas of data on the ring.
>>>
>>> What happen in the case of all nodes containing replicas are down ?
>>>
>>>
>>> Thank you so much for help.
>>>
>>> Kind regards.
>>>
>>
>>
>
--
Benjamin Roth
Prokurist
Jaumo GmbH · www.jaumo.com
Wehrstraße 46 · 73035 Göppingen · Germany
Phone +49 7161 304880-6 · Fax +49 7161 304880-1
AG Ulm · HRB 731058 · Managing Director: Jens Kammerer
Re: All nodes hosting replicas down
Posted by jean paul <re...@gmail.com>.
Thank you so much for answer.
So, in case of a high failure rate in my cluster, i have to increase the
replication factor or i have to use NetworkToplogy Strategy ?
That's it ?
Kindly.
2016-12-18 20:23 GMT+01:00 Matija Gobec <ma...@gmail.com>:
> If you are reading and none of the replicas is online you will get an
> exception on the read (tried x replicas but 0 responded) and your read will
> fail. Writes on the other hand are going to go through only if your write
> consistency is ANY. If your write consistency is ONE or anything upwards,
> then it will fail too.
>
> On Sun, Dec 18, 2016 at 7:47 PM, jean paul <re...@gmail.com> wrote:
>
>> Hi,
>>
>> Please, if we choose a replication factor =2 (simple strategy), so, we
>> have two replicas of data on the ring.
>>
>> What happen in the case of all nodes containing replicas are down ?
>>
>>
>> Thank you so much for help.
>>
>> Kind regards.
>>
>
>
Re: All nodes hosting replicas down
Posted by Matija Gobec <ma...@gmail.com>.
If you are reading and none of the replicas is online you will get an
exception on the read (tried x replicas but 0 responded) and your read will
fail. Writes on the other hand are going to go through only if your write
consistency is ANY. If your write consistency is ONE or anything upwards,
then it will fail too.
On Sun, Dec 18, 2016 at 7:47 PM, jean paul <re...@gmail.com> wrote:
> Hi,
>
> Please, if we choose a replication factor =2 (simple strategy), so, we
> have two replicas of data on the ring.
>
> What happen in the case of all nodes containing replicas are down ?
>
>
> Thank you so much for help.
>
> Kind regards.
>