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From Edmond Lau <>
Subject Re: backing up data from cassandra
Date Tue, 06 Oct 2009 18:28:27 GMT
Thanks for the replies guys.  It sounds like restoration via snapshots
+ some application-side logic to sanity check/repair any data around
the snapshot time is the way to go.


On Mon, Oct 5, 2009 at 10:15 AM, Jonathan Ellis <> wrote:
> On Mon, Oct 5, 2009 at 11:23 AM, Thorsten von Eicken <> wrote:
>> Isn't the question about how you back up a cassandra cluster, not a
>> single node?
> Sure, but the generalization is straightforward. :)
>> Can you snapshot the various nodes at different times or do
>> they need to be synchronized?
> The closer the synchronization, the more consistent they will be.
> (Since Cassandra is designed around eventual consistency, there's some
> flexibility here.  Conversely, there's no way to tell the system
> "don't accept any more writes until the snapshot is done.")
>> Is there a minimal set of nodes that are
>> sufficient to back up?
> Assuming your replication is 100% up to date, backing up every N nodes
> where N is the replication factor could be adequate in theory, but I
> wouldn't recommend trying to be clever like that, since if you
> "restored" from backup like that your system would be in a degraded
> state and vulnerable to any of the restored nodes failing.
> -Jonathan

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