Re: 回复： data loss in different DC

[Reynald Bourtembourg]

Do you mean how often we should run repairs in this situation (write at 
CL=EACH_QUORUM and CL=LOCAL_QUORUM)?


I don't consider myself as an expert in this domain, so I will let the 
real experts answer to this question...
You can also refer to this mailing list history (many threads on this 
snbject) and to the recommendations in the documentation:

http://cassandra.apache.org/doc/latest/operating/repair.html#usage-and-best-practices

Kind regards
Reynald


On 28/09/2017 14:49, Jacob Shadix wrote:

How often are you running repairs?

-- Jacob Shadix

On Thu, Sep 28, 2017 at 7:53 AM, Reynald Bourtembourg 
> 
wrote:


Hi,

You can write with CL=EACH_QUORUM and read with CL=LOCAL_QUORUM to
get strong consistency.

Kind regards,
Reynald


On 28/09/2017 13:46, Peng Xiao wrote:

even with CL=QUORUM,there is no guarantee to be sure to read the
same data in DC2,right?
then multi DCs looks make no sense?


-- 原始邮件 --
*发件人:* "DuyHai Doan";
;
*发送时间:* 2017年9月28日(星期四) 下午5:45
*收件人:* "user"
;
*主题:* Re: data loss in different DC

If you're writing into DC1 with CL = LOCAL_xxx, there is no
guarantee to be sure to read the same data in DC2. Only repair
will help you

On Thu, Sep 28, 2017 at 11:41 AM, Peng Xiao <2535...@qq.com
> wrote:

Dear All,

We have a cluster with one DC1:RF=3,another DC DC2:RF=1 only
for ETL,but we found that sometimes we can query records in
DC1,while not able not find the same record in DC2 with
local_quorum.How it happens?
Could anyone please advise?
looks we can only run repair to fix it.

Thanks,
Peng Xiao

Re: 回复： data loss in different DC

[Jacob Shadix]

How often are you running repairs?

-- Jacob Shadix

On Thu, Sep 28, 2017 at 7:53 AM, Reynald Bourtembourg <
reynald.bourtembo...@esrf.fr> wrote:

> Hi,
>
> You can write with CL=EACH_QUORUM and read with CL=LOCAL_QUORUM to get
> strong consistency.
>
> Kind regards,
> Reynald
>
>
> On 28/09/2017 13:46, Peng Xiao wrote:
>
> even with CL=QUORUM,there is no guarantee to be sure to read the same data
> in DC2,right?
> then multi DCs looks make no sense?
>
>
> -- 原始邮件 --
> *发件人:* "DuyHai Doan"; ;
> *发送时间:* 2017年9月28日(星期四) 下午5:45
> *收件人:* "user" ;
> *主题:* Re: data loss in different DC
>
> If you're writing into DC1 with CL = LOCAL_xxx, there is no guarantee to
> be sure to read the same data in DC2. Only repair will help you
>
> On Thu, Sep 28, 2017 at 11:41 AM, Peng Xiao <2535...@qq.com> wrote:
>
>> Dear All,
>>
>> We have a cluster with one DC1:RF=3,another DC DC2:RF=1 only for ETL,but
>> we found that sometimes we can query records in DC1,while not able not find
>> the same record in DC2 with local_quorum.How it happens?
>> Could anyone please advise?
>> looks we can only run repair to fix it.
>>
>> Thanks,
>> Peng Xiao
>>
>
>
>

Re: 回复： data loss in different DC

[Reynald Bourtembourg]

Hi,

You can write with CL=EACH_QUORUM and read with CL=LOCAL_QUORUM to get 
strong consistency.


Kind regards,
Reynald

On 28/09/2017 13:46, Peng Xiao wrote:
even with CL=QUORUM,there is no guarantee to be sure to read the same 
data in DC2,right?

then multi DCs looks make no sense?


--?0?2?0?2--
*??:*?0?2"DuyHai Doan";;
*:*?0?22017??9??28??(??) 5:45
*??:*?0?2"user";
*:*?0?2Re: data loss in different DC

If you're writing into DC1 with CL = LOCAL_xxx, there is no guarantee 
to be sure to read the same data in DC2. Only repair will help you


On Thu, Sep 28, 2017 at 11:41 AM, Peng Xiao <2535...@qq.com 
> wrote:


Dear All,

We have a cluster with one DC1:RF=3,another DC DC2:RF=1 only for
ETL,but we found that sometimes we can query records in DC1,while
not able not find the same record in DC2 with local_quorum.How it
happens?
Could anyone please advise?
looks we can only run repair to fix it.

Thanks,
Peng Xiao