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From Petr Malik <>
Subject Single cluster node restore
Date Tue, 29 Nov 2016 17:38:19 GMT


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.


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