Cross DC replication failing

[Inquistive allen <in...@gmail.com>]

Hello team,
Greetings.

Simple question

Using Cassandra 3.0.8
Writing to DC-A using local_quorum
Reading the same data from a DC-B using local quorum.

It succeeds for a table and fails for other.
Data written is not replicated immediately even after a long time.
However if read is performed using a quorum we fetch data.

I do understand what is happening

Any idea
1. How to track how many messages are yet to be replicated
2. Any way to understand why they are not getting replicated across DC
3. I know I can force a sync by repair but this cross DC replication is
expected to be automatic. Am I correct?

Thanks

Re: Cross DC replication failing

[Jeff Jirsa <jj...@gmail.com>]

> On Nov 13, 2021, at 10:25 AM, Inquistive allen <in...@gmail.com> wrote:
> 
> 
> Hello team,
> Greetings.
> 
> Simple question
> 
> Using Cassandra 3.0.8
> Writing to DC-A using local_quorum
> Reading the same data from a DC-B using local quorum.
> 
> It succeeds for a table and fails for other.
> Data written is not replicated immediately even after a long time.
> However if read is performed using a quorum we fetch data.
> 
> I do understand what is happening
> 
> Any idea
> 1. How to track how many messages are yet to be replicated

Potentially pending hints but not really



> 2. Any way to understand why they are not getting replicated across DC

Logs and tracing

> 3. I know I can force a sync by repair but this cross DC replication is expected to be automatic. Am I correct?


Yes
This is probably some form of bug or configuration error. 3.0.8 is quite old and has a lot of known bugs, I’d start by upgrading to newest 3.0 or 3.11 or 4.0