If you don't need synchronnous replication then asynchronnous is the way to go, 
but Ceph doesn't offer that natively. (not for RBD anyway, not sure how radosgw 
could be set up).

200km will add at least 1ms of latency network-wise, 2ms RTT, for TCP it will 
be more.
For sync replication (which ceph offers natively) this is high, and you also 
need a 0% packetloss. Unless you have your own fibre I recommend against it.

I suggest you replicate data on application level (databases) or incremental 
replication of filesystems (ZFS). You can also use Ceph snapshots and replicate 
those.

Before you decide on any design you should know your RPO/RTO/RCO requirements 
to decide what is sufficient.

Jan


> On 10 Dec 2015, at 17:17, Andrea Annoè <andrea.an...@iks.it> wrote:
> 
> Hi to all
> Someone has news about Geo-replication?
>  
> I have find this really nice article by Sebastien 
> http://www.sebastien-han.fr/blog/2013/01/28/ceph-geo-replication-sort-of/ 
> <http://www.sebastien-han.fr/blog/2013/01/28/ceph-geo-replication-sort-of/> 
> but it’s 3 years ago…
> My question is about configuration (and limitation : TTL, distance, flapping 
> network consideration, ecc…) for create this geo-replication.
>  
> If my dual site is distance about 200km …what do you suggest?
> Replica synchrony or asynchrony ? 
>  
> Thanks in advance to all for your opinion.
>  
> Best Regards Andrea.
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