Hi.

I have a question about Cassandra backup-restore strategies.


As far as I understand Cassandra has been designed to survive hardware failures 
by relying on data replication.


It seems like people still want backup/restore for case when somebody 
accidentally deletes data or the data gets otherwise corrupted.

In that case restoring all keyspace/table snapshots on all nodes should bring 
it back.


I am asking because I often read directions on restoring a single node in a 
cluster. I am just wondering under what circumstances could this be done safely.


Please correct me if i am wrong but restoring just a single node does not 
really roll back the data as the newer (corrupt) data will be served by other 
replicas and eventually propagated to the restored node. Right?

In fact by doing so one may end up reintroducing deleted data back...


Also since Cassandra distributes the data throughout the cluster it is not 
clear on which mode any particular (corrupt) data resides and hence which to 
restore.


I guess this is a long way of asking whether there is an advantage of trying to 
restore just a single node in a Cassandra cluster as opposed to say replacing 
the dead node and letting Cassandra handle the replication.


Thanks.

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