> If using the SimpleStrategy replication class, it appears that
> replication_factor is the only option, which applies to the entire
> cluster, so only one node in both datacenters would have the data.
This runs counter to my understanding, or else I'm not reading your
statement correctly. When a user chooses SimpleStrategy they're saying
that the same replication applies to _each DC_ in your cluster, not that
_all DC's_ contribute to the total replication.
Put another way, my understanding is that if you have SimpleStrategy RF=1
with two data centers, you have two copies of each piece of data - one in
each DC.
On Thu, Jul 20, 2017 at 2:56 PM Michael Shuler <mich...@pbandjelly.org>
wrote:
> Datacenter replication is defined in the keyspace schema, so I believe that
> ...
> WITH replication = {'class': 'NetworkTopologyStrategy', 'DC1': 1,
> 'DC2': 1}
> ...
> you ought to be able to repair DC1 from DC2, once you have the DC1 node
> healthy again.
>
> If using the SimpleStrategy replication class, it appears that
> replication_factor is the only option, which applies to the entire
> cluster, so only one node in both datacenters would have the data.
>
> https://cassandra.apache.org/doc/latest/cql/ddl.html#create-keyspace
>
> --
> Kind regards,
> Michael
>
> On 07/20/2017 03:23 PM, Roger Warner wrote:
> > Hi
> >
> >
> >
> > I’m a little dim on what multi datacenter implies in the 1 replica
> > case. I know about replica recovery, how about “node recovery”
> >
> >
> >
> > As I understand if there a node failure or disk crash with a single node
> > cluster with replication factor 1 I lose data. Easy.
> >
> >
> >
> > nodetool tells me each node in my 3 node X 2 datacenters is responsible
> > for ~1/3 of the data. If in this cluster with RF=1 a node fails in
> > dc1 what happens ? in 1 dc with data loss can the node be “restored”
> > from a node in dc2?. Automatically?
> >
> >
> >
> > I’m also asking tangentially how does the data map from nodes in dc1 to
> > dc2.
> >
> >
> >
> > I hope I made that coherent.
> >
> >
> >
> > Roger
> >
>
>
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